All questions of Motion and Time for Class 7 Exam

Circumference of circle

**Answer:**

The correct answer is option D, both (a) and (b).

**Explanation:**

Uniform motion is the type of motion in which an object covers equal distances in equal intervals of time. In other words, the object moves at a constant speed in a straight line. Let's analyze each option to determine if it represents uniform motion or not:

a) A swinging pendulum:
A swinging pendulum does not represent uniform motion because its speed is not constant. A pendulum swings back and forth, and its speed changes at each point in its swing. The speed is maximum at the lowest point (the equilibrium position) and decreases as it moves upward. Therefore, a swinging pendulum is not an example of uniform motion.

b) The rotation of the Earth:
The rotation of the Earth does not represent uniform motion because the Earth is not moving at a constant speed in a straight line. The Earth rotates on its axis, completing one rotation in approximately 24 hours. However, the speed of rotation is not constant. The Earth moves faster at the equator and slower at the poles. Therefore, the rotation of the Earth is not an example of uniform motion.

c) A bullet traveling with a constant speed in a straight line:
A bullet traveling with a constant speed in a straight line represents uniform motion. If a bullet is traveling at a constant speed, covering equal distances in equal intervals of time, it is an example of uniform motion.

Therefore, options a and b are not in uniform motion, while option c represents uniform motion. Hence, the correct answer is option D, both (a) and (b).

The answer is D. The answer is that because all are in a straight line on the graph except the last one because it is slanting. Also constant speed does not accelerate or decelerate on the graph but goes in the same speed for the whole time.
please upvote to me and my answer!!!!!

Understanding Speed Conversion
To convert speed from kilometers per hour (km/h) to meters per second (m/s), we need to understand the relationship between these two units.
Conversion Factor
- 1 kilometer = 1000 meters
- 1 hour = 3600 seconds
Therefore, to convert km/h to m/s, we can use the following formula:
Conversion Formula
- Speed in m/s = Speed in km/h × (1000 meters / 1 kilometer) × (1 hour / 3600 seconds)
This simplifies to:
- Speed in m/s = Speed in km/h × (1000 / 3600)
Performing the Calculation
Now, let's convert 180 km/h to m/s:
- Speed in m/s = 180 km/h × (1000 / 3600)
Calculating this:
- Speed in m/s = 180 × (1000 / 3600)
- Speed in m/s = 180 × (1 / 3.6)
- Speed in m/s = 180 / 3.6
- Speed in m/s = 50 m/s
Conclusion
Thus, the speed of the jet moving at 180 km/h is equivalent to 50 m/s.
The correct answer is:
Option A: 50 m/s

Understanding Distance and Displacement
Distance and displacement are fundamental concepts in physics that describe the movement of an object.
Distance
- It refers to the total path length traveled by an object, regardless of its direction.
- It is a scalar quantity, meaning it only has magnitude and no direction.
Displacement
- Displacement is the shortest distance from the initial to the final position of an object, along with the direction.
- It is a vector quantity, which means it has both magnitude and direction.
When Do Distance and Displacement Equal Each Other?
- The distance traveled is equal to the displacement when the object moves in a straight line without changing direction.
- In such cases, the path taken by the object is a straight line from the starting point to the endpoint.
Why Option A is Correct
- Straight Line Movement: If an object moves in a straight line in a forward direction, the distance it covers and the straight-line distance from the starting point to the endpoint are identical.
- No Changes in Direction: Since there are no changes in direction, the total path length equals the direct distance between the two points.
Other Options Explained
- Option B: If the object is moving in different directions, the distance will be greater than the displacement.
- Option C: Movement along any path, especially if it's not straight, will result in a larger distance than displacement.
- Option D: It is indeed possible for distance to equal displacement under specific conditions, such as straight-line movement.
In conclusion, option A is the correct answer because it accurately describes the condition under which distance and displacement are equal.

Distance because time and speed is already there but if we think speed and time it is distance.

([A] DISTANCE)

The CGS unit of speed is cm/s.