Class 7 Science Chapter 9 Question Answers - Motion and Time

Q1: The basic unit of speed is

(i) Km/ min

(ii) m/ min

(iii) Km/ sec

(iv) m/ sec

Ans : (iv) m/ sec

Speed is defined as the rate at which an object covers distance. It is measured in terms of how much distance is traveled per unit of time. In the metric system, the unit for distance is meters (m) and the unit for time is seconds (sec). Therefore, the basic unit of speed is meters per second (m/sec).

Q2: What is motion?

Ans : Motion is a change in the position of an object with time.

Q3: Define average speed.

Ans : The average speed of a moving object is defined as the total distance covered by it divided by the total time taken.

Q4: What do you mean by the statement; “car is moving with the speed of 50 Km per hour”?

Ans : Car is moving with the speed of 50 Km per hour it means it will cover a distance of 50 Km in one hour

Q5: What is a simple pendulum's periodic motion?

Ans: A simple pendulum's periodic motion involves oscillations back and forth from a center point.

Q6: What information can be interpreted from a distance-time graph?

Ans: A distance-time graph shows how distance changes over time and can reveal information about an object's speed and direction of motion.

Q7: How do you define uniform motion?

Ans: Uniform motion occurs when an object moves along a straight line with a constant speed.

Q8: What is the time period of a simple pendulum?

Ans: The time period of a simple pendulum is the time taken for the pendulum to complete one full oscillation.

Q9: What is periodic motion, and how is it related to measuring time?

Ans: Periodic motion is a repetitive motion that occurs at regular intervals. It is essential for measuring time accurately, as in the case of clocks.

Q10: How do we measure speed using a speedometer and an odometer?

Ans: Speedometers measure and display the speed of a vehicle in km/h, while odometers record the distance traveled by the vehicle in kilometers (km).

Q11: The metallic ball in pendulum is called __________ of the pendulum. 

Ans : Bob

Q12: Give an example of oscillatory motion. 

Ans : To and fro motion of a simple pendulum

Q13: Motion along a curved path is called _______________. 

Ans : curvilinear motion

Q14: Name the device used to measure speed. 

Ans : Speedometer

Q15: Motion of the hammer of an electric bell is ___________________ motion.

 Ans : Oscillatory motion