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All questions of Motion and Time for Class 7 Exam
A car is moving with 72 km/hrs. The speed of the car in m/s is
- a)30 m/s
- b)20 m/s
- c)40 m/s
- d)25 m/s
Correct answer is option 'B'. Can you explain this answer?
A car is moving with 72 km/hrs. The speed of the car in m/s is
a)
30 m/s
b)
20 m/s
c)
40 m/s
d)
25 m/s
|
Meera Reddy answered |
We know ,
1 km=1000m , 1 hour=3600s
1km/h=1000/3600m/s=5/18m/s
72km/h=72×5/18m/s
=4×5m/s
=20m/s.
1 km=1000m , 1 hour=3600s
1km/h=1000/3600m/s=5/18m/s
72km/h=72×5/18m/s
=4×5m/s
=20m/s.
The speed of the vehicle is recorded by
- a)Ammeter
- b)Odometer
- c)Speedometer
- d)Voltmeter
Correct answer is option 'C'. Can you explain this answer?
The speed of the vehicle is recorded by
a)
Ammeter
b)
Odometer
c)
Speedometer
d)
Voltmeter
|
Jyoti Kulkarni answered |
- The speedometer is a device found in vehicles that measures the current speed of the vehicle.
- It provides real-time information, allowing drivers to maintain safe speeds and abide by traffic regulations.
- Unlike an odometer, which measures distance traveled, the speedometer focuses solely on speed.
- Ammeter and voltmeter measure electrical current and voltage, respectively, and are not related to vehicle speed.
Topic in NCERT: Measuring Speed
Line in NCERT: "The speedometer records the speed directly in km/h."
Change in position with respect to the surroundings is called
- a)Acceleration
- b)Speed
- c)Momentum
- d)Force
Correct answer is option 'B'. Can you explain this answer?
Change in position with respect to the surroundings is called
a)
Acceleration
b)
Speed
c)
Momentum
d)
Force
|
Lakshmi Reddy answered |
The change in position with respect to the surroundings is called Speed
- Speed is the measure of how quickly an object moves from one position to another. It is calculated as the distance traveled divided by the time taken to travel that distance.
Line in NCERT: "The distance moved by an object in a unit time is called its speed."
The earliest clocks for measuring time during day were
- a)Sand clocks
- b)Pendulum clocks
- c)Sundials
- d)Stop watches
Correct answer is option 'C'. Can you explain this answer?
The earliest clocks for measuring time during day were
a)
Sand clocks
b)
Pendulum clocks
c)
Sundials
d)
Stop watches
|
Aditi Rane answered |
Sundials were used for measuring time in earlier days on the basis of shadow position.
Topic in NCERT: Units of time and speed
Line in NCERT: "Sundials"
The basic unit of speed is:
- a)km/min
- b)m/min
- c)km/h
- d)m/s
Correct answer is option 'D'. Can you explain this answer?
The basic unit of speed is:
a)
km/min
b)
m/min
c)
km/h
d)
m/s
|
Kavya Rane answered |
The basic unit of distance is metre (m). The basic unit of time is second (s). Since we know that s=d/t. Therefore, the basic unit of speed is m/s.
So option D is the correct answer.
Speed time graph is straight line for- a)Non-uniform motion
- b)Constant motion Uniform motion
- c)Uniform motion
- d)Accelerated motion
Correct answer is option 'C'. Can you explain this answer?
Speed time graph is straight line for
a)
Non-uniform motion
b)
Constant motion Uniform motion
c)
Uniform motion
d)
Accelerated motion
|
Kiran Bajaj answered |
When the slope of distance-time graph is a straight line parallel to time axis, the object is moving with uniform motion.
What is the speed of a car that travels 15 km in 20 minutes, expressed in km/h?
- a)35 km/h
- b)40 km/h
- c)45 km/h
- d)50 km/h
Correct answer is option 'C'. Can you explain this answer?
What is the speed of a car that travels 15 km in 20 minutes, expressed in km/h?
a)
35 km/h
b)
40 km/h
c)
45 km/h
d)
50 km/h
|
Vidhi bajaj answered |
Calculation:
- Distance traveled = 15 km
- Time taken = 20 minutes = 20/60 hours = 1/3 hours
Formula:
- Speed = Distance/Time
Calculation:
- Speed = 15 km / (1/3) hours
- Speed = 15 km * 3
- Speed = 45 km/h
Therefore, the speed of the car that travels 15 km in 20 minutes is 45 km/h.
- Distance traveled = 15 km
- Time taken = 20 minutes = 20/60 hours = 1/3 hours
Formula:
- Speed = Distance/Time
Calculation:
- Speed = 15 km / (1/3) hours
- Speed = 15 km * 3
- Speed = 45 km/h
Therefore, the speed of the car that travels 15 km in 20 minutes is 45 km/h.
A scooterist travels at 30 km/h along straight path for 20 min. What is distance?- a)10 km
- b)1.5 km
- c)6 km
- d)90 km
Correct answer is option 'A'. Can you explain this answer?
A scooterist travels at 30 km/h along straight path for 20 min. What is distance?
a)
10 km
b)
1.5 km
c)
6 km
d)
90 km
|
Praveen Kumar answered |
If the scooter is travelling at precisely 30km/h in a perfectly straight line.
We know 1 hour=60 minutes
Therefore to calculate the distance traveled in the started fraction of the hour.
Therefore 10km is the distance traveled in 20 minutes of travelling at a speed of 30km/h
We know 1 hour=60 minutes
Therefore to calculate the distance traveled in the started fraction of the hour.
Therefore 10km is the distance traveled in 20 minutes of travelling at a speed of 30km/h
Which of the following motions is characterized by an object moving back and forth along the same path?- a)Circular motion
- b)Linear motion
- c)Oscillatory motion
- d)Random motion
Correct answer is option 'C'. Can you explain this answer?
a)
Circular motion
b)
Linear motion
c)
Oscillatory motion
d)
Random motion
|
|
Vaibhav Goyal answered |
Understanding Oscillatory Motion
Oscillatory motion is a specific type of movement where an object moves back and forth along the same path. This motion can be observed in various everyday scenarios and is characterized by a repetitive cycle.
Key Characteristics of Oscillatory Motion:
- Back and Forth Movement: The defining feature of oscillatory motion is that the object returns to its original position after moving in one direction, then reverses to move in the opposite direction.
- Examples: Common examples include a swinging pendulum, vibrations of a guitar string, or the motion of a spring when compressed and released.
- Time Period: This motion is periodic, meaning it occurs in cycles over a fixed time interval, known as the time period.
- Equilibrium Position: The object oscillates around a central point or equilibrium position, where it would be at rest if not for the oscillatory forces acting on it.
Why Other Motions Are Not Oscillatory:
- Circular Motion: In circular motion, an object moves in a circular path, which does not involve returning along the same path.
- Linear Motion: Linear motion involves movement in a straight line, without the back-and-forth characteristic of oscillatory motion.
- Random Motion: Random motion lacks any predictable pattern, unlike the orderly back-and-forth nature of oscillatory motion.
In summary, oscillatory motion is distinct due to its repetitive back-and-forth movement along the same path, making option 'C' the correct answer.
Oscillatory motion is a specific type of movement where an object moves back and forth along the same path. This motion can be observed in various everyday scenarios and is characterized by a repetitive cycle.
Key Characteristics of Oscillatory Motion:
- Back and Forth Movement: The defining feature of oscillatory motion is that the object returns to its original position after moving in one direction, then reverses to move in the opposite direction.
- Examples: Common examples include a swinging pendulum, vibrations of a guitar string, or the motion of a spring when compressed and released.
- Time Period: This motion is periodic, meaning it occurs in cycles over a fixed time interval, known as the time period.
- Equilibrium Position: The object oscillates around a central point or equilibrium position, where it would be at rest if not for the oscillatory forces acting on it.
Why Other Motions Are Not Oscillatory:
- Circular Motion: In circular motion, an object moves in a circular path, which does not involve returning along the same path.
- Linear Motion: Linear motion involves movement in a straight line, without the back-and-forth characteristic of oscillatory motion.
- Random Motion: Random motion lacks any predictable pattern, unlike the orderly back-and-forth nature of oscillatory motion.
In summary, oscillatory motion is distinct due to its repetitive back-and-forth movement along the same path, making option 'C' the correct answer.
Which of the following is an example of non-uniform motion?- a)Movement of an asteroid
- b)A car coming to a halt
- c)A bouncing ball
- d)All of these
Correct answer is option 'D'. Can you explain this answer?
Which of the following is an example of non-uniform motion?
a)
Movement of an asteroid
b)
A car coming to a halt
c)
A bouncing ball
d)
All of these
|
|
Aryan Mukherjee answered |
Non-uniform Motion:
Movement of an asteroid, a car coming to a halt, and a bouncing ball are all examples of non-uniform motion. Non-uniform motion refers to an object moving at varying speeds or changing its direction over time.
Movement of an Asteroid:
- An asteroid moving through space does not maintain a constant speed as it is influenced by gravitational forces from other celestial bodies. It may speed up or slow down as it travels through the solar system.
A Car Coming to a Halt:
- When a car is slowing down to come to a stop, it is experiencing non-uniform motion. Initially, the car is moving at a certain speed, but as the brakes are applied, the speed decreases until it eventually comes to a complete stop.
A Bouncing Ball:
- A bouncing ball is another example of non-uniform motion. When a ball is thrown or dropped, it accelerates towards the ground due to gravity. Upon hitting the ground, it bounces back up, changing its speed and direction multiple times during the bouncing process.
Conclusion:
- All three examples exhibit non-uniform motion because they involve changes in speed or direction over time. Understanding non-uniform motion is essential in physics as it helps to describe the motion of objects in real-world scenarios.
The distance-time graph of the non-uniform motion is a _________ line- a)straight
- b)straight then curved
- c)curved
- d)none of these
Correct answer is option 'C'. Can you explain this answer?
The distance-time graph of the non-uniform motion is a _________ line
a)
straight
b)
straight then curved
c)
curved
d)
none of these
|
|
Aryan Mukherjee answered |
Distance-Time Graph
A distance-time graph is a graphical representation that shows how the distance traveled by an object changes over time. The distance is plotted on the y-axis, while the time is plotted on the x-axis. The shape of the graph can provide information about the type of motion exhibited by the object.
Uniform Motion
In uniform motion, an object covers equal distances in equal intervals of time. This means that the object is moving at a constant speed. The distance-time graph for uniform motion is a straight line. The slope of the line represents the speed of the object. The steeper the slope, the faster the object is moving.
Non-Uniform Motion
In non-uniform motion, an object covers unequal distances in equal intervals of time. This means that the object is changing its speed. The distance-time graph for non-uniform motion is a curved line. The curvature of the line indicates that the object is either accelerating or decelerating.
Explanation of the Correct Answer
The correct answer is option 'C' - curved. This means that the distance-time graph of non-uniform motion is a curved line. This is because in non-uniform motion, the object is changing its speed. It may be accelerating, decelerating, or following any other pattern that does not result in equal distances covered in equal intervals of time.
When an object accelerates, it covers increasing distances in equal intervals of time. This results in a curve that is upward sloping. The steeper the curve, the faster the object is accelerating. On the other hand, when an object decelerates, it covers decreasing distances in equal intervals of time. This results in a curve that is downward sloping.
In addition to acceleration and deceleration, the graph may also have other shapes depending on the specific motion of the object. For example, the graph may have multiple curves, indicating changes in acceleration or direction.
Therefore, the distance-time graph of non-uniform motion is a curved line, as it represents the changing speeds and distances covered by the object over time.
A distance-time graph is a graphical representation that shows how the distance traveled by an object changes over time. The distance is plotted on the y-axis, while the time is plotted on the x-axis. The shape of the graph can provide information about the type of motion exhibited by the object.
Uniform Motion
In uniform motion, an object covers equal distances in equal intervals of time. This means that the object is moving at a constant speed. The distance-time graph for uniform motion is a straight line. The slope of the line represents the speed of the object. The steeper the slope, the faster the object is moving.
Non-Uniform Motion
In non-uniform motion, an object covers unequal distances in equal intervals of time. This means that the object is changing its speed. The distance-time graph for non-uniform motion is a curved line. The curvature of the line indicates that the object is either accelerating or decelerating.
Explanation of the Correct Answer
The correct answer is option 'C' - curved. This means that the distance-time graph of non-uniform motion is a curved line. This is because in non-uniform motion, the object is changing its speed. It may be accelerating, decelerating, or following any other pattern that does not result in equal distances covered in equal intervals of time.
When an object accelerates, it covers increasing distances in equal intervals of time. This results in a curve that is upward sloping. The steeper the curve, the faster the object is accelerating. On the other hand, when an object decelerates, it covers decreasing distances in equal intervals of time. This results in a curve that is downward sloping.
In addition to acceleration and deceleration, the graph may also have other shapes depending on the specific motion of the object. For example, the graph may have multiple curves, indicating changes in acceleration or direction.
Therefore, the distance-time graph of non-uniform motion is a curved line, as it represents the changing speeds and distances covered by the object over time.
Car travels first 60 km of a distance in 1 hr, next 70 km of the distance in next hour and remaining 20 km distance in final hour. Find its type of motion
- a)uniform motion
- b)non-uniform motion
- c)either uniform or non-uniform motion
- d)neither uniform nor non-uniform motion
Correct answer is option 'B'. Can you explain this answer?
Car travels first 60 km of a distance in 1 hr, next 70 km of the distance in next hour and remaining 20 km distance in final hour. Find its type of motion
a)
uniform motion
b)
non-uniform motion
c)
either uniform or non-uniform motion
d)
neither uniform nor non-uniform motion
|
|
Praveen Kumar answered |
So, the car travels different distances in equal time intervals. This is an example of non-uniform motion.
Rajdhini express moves at a speed of 150 km/h. How long will it take to cover a distance of 15 km?- a)1.125 h
- b)2.125 h
- c)3.125 h
- d)0.1 h
Correct answer is option 'D'. Can you explain this answer?
Rajdhini express moves at a speed of 150 km/h. How long will it take to cover a distance of 15 km?
a)
1.125 h
b)
2.125 h
c)
3.125 h
d)
0.1 h
|
Aryan Roy answered |
Given Information:
Rajdhani Express moves at a speed of 150 km/h.
The distance to be covered is 15 km.
To Find:
The time taken to cover the distance of 15 km.
Solution:
To find the time taken to cover a distance, we can use the formula:
Time = Distance / Speed
Given that the distance is 15 km and the speed is 150 km/h, we can substitute these values into the formula to find the time:
Time = 15 km / 150 km/h
Calculation:
Time = 0.1 hour
Therefore, it will take 0.1 hour to cover a distance of 15 km.
Answer:
The correct answer is option D) 0.1 hour.
If a simple pendulum completes 20 oscillations in 32 seconds, what is its time period?
- a)1.6 s
- b)2.0 s
- c)2.5 s
- d)3.2 s
Correct answer is option 'A'. Can you explain this answer?
If a simple pendulum completes 20 oscillations in 32 seconds, what is its time period?
a)
1.6 s
b)
2.0 s
c)
2.5 s
d)
3.2 s
|
|
Trisha malhotra answered |
Understanding the Problem
To find the time period of a simple pendulum, we need to understand the relationship between the number of oscillations and the total time taken for those oscillations.
Given Data
- Total oscillations = 20
- Total time = 32 seconds
Calculating Time Period
The time period (T) of a pendulum is defined as the time it takes to complete one full oscillation. We can calculate it using the formula:
Now, substituting the given values into the formula:
Conclusion
Thus, the time period of the pendulum is 1.6 seconds. Therefore, the correct answer is option 'A'.
Key Takeaways
- The time period indicates how long it takes for one complete oscillation.
- This calculation is essential in understanding the dynamics of pendulums, which are a fundamental concept in physics.
With this understanding, you can confidently solve similar problems involving simple harmonic motion and pendulums!
To find the time period of a simple pendulum, we need to understand the relationship between the number of oscillations and the total time taken for those oscillations.
Given Data
- Total oscillations = 20
- Total time = 32 seconds
Calculating Time Period
The time period (T) of a pendulum is defined as the time it takes to complete one full oscillation. We can calculate it using the formula:
- Time Period (T) = Total Time / Number of Oscillations
Now, substituting the given values into the formula:
- T = 32 seconds / 20 oscillations
- T = 1.6 seconds
Conclusion
Thus, the time period of the pendulum is 1.6 seconds. Therefore, the correct answer is option 'A'.
Key Takeaways
- The time period indicates how long it takes for one complete oscillation.
- This calculation is essential in understanding the dynamics of pendulums, which are a fundamental concept in physics.
With this understanding, you can confidently solve similar problems involving simple harmonic motion and pendulums!
A train travels at a speed of 60 km/h. How far will it travel in 4 hours?- a)15 km
- b)230 km
- c)60km
- d)240km
Correct answer is option 'D'. Can you explain this answer?
A train travels at a speed of 60 km/h. How far will it travel in 4 hours?
a)
15 km
b)
230 km
c)
60km
d)
240km
|
Coachify answered |
- The speed of the train is 60 km/h.
- The train travels for 4 hours.
- Distance is calculated using the formula: Distance = Speed × Time.
- Substitute the values: Distance = 60 km/h × 4 hours = 240 km.
- Thus, the train will travel 240 km in 4 hours
Correct Answer -Option D
Which of the following does not express a time interval?- a)Time of the first bell in the school
- b)A day
- c)A second
- d)A school period
Correct answer is option 'A'. Can you explain this answer?
Which of the following does not express a time interval?
a)
Time of the first bell in the school
b)
A day
c)
A second
d)
A school period
|
|
Sunehri Choudhary answered |
Explanation:
The correct answer is option 'A' - Time of the first bell in the school.
Time intervals:
Time intervals refer to a specific duration or period of time. They measure the amount of time between two points or events.
Options:
a) Time of the first bell in the school:
This option does not express a time interval. It refers to a specific point in time when the first bell rings in the school. It does not indicate a duration or a period of time. Therefore, it is not an example of a time interval.
b) A day:
A day represents a time interval. It refers to a period of 24 hours, starting from midnight and ending at the next midnight. It is a commonly used unit of time to measure the duration of various activities or events.
c) A second:
A second is another example of a time interval. It is a unit of time measurement in the International System of Units (SI). It represents a duration of 1/60th of a minute or 1/3,600th of an hour. It is commonly used to measure short durations or intervals.
d) A school period:
A school period is also a time interval. It refers to a specific duration of time allocated for a particular subject or activity in a school. It can vary in length depending on the school's schedule and may range from a few minutes to an hour.
Conclusion:
Out of the given options, the only one that does not express a time interval is option 'A' - Time of the first bell in the school. This option refers to a specific point in time rather than a duration or period of time.
The correct answer is option 'A' - Time of the first bell in the school.
Time intervals:
Time intervals refer to a specific duration or period of time. They measure the amount of time between two points or events.
Options:
a) Time of the first bell in the school:
This option does not express a time interval. It refers to a specific point in time when the first bell rings in the school. It does not indicate a duration or a period of time. Therefore, it is not an example of a time interval.
b) A day:
A day represents a time interval. It refers to a period of 24 hours, starting from midnight and ending at the next midnight. It is a commonly used unit of time to measure the duration of various activities or events.
c) A second:
A second is another example of a time interval. It is a unit of time measurement in the International System of Units (SI). It represents a duration of 1/60th of a minute or 1/3,600th of an hour. It is commonly used to measure short durations or intervals.
d) A school period:
A school period is also a time interval. It refers to a specific duration of time allocated for a particular subject or activity in a school. It can vary in length depending on the school's schedule and may range from a few minutes to an hour.
Conclusion:
Out of the given options, the only one that does not express a time interval is option 'A' - Time of the first bell in the school. This option refers to a specific point in time rather than a duration or period of time.
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