# NCERT Class VII Science Solutions: Chapter 13-Motion and Time Part 1

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Question 1:

Classify the following as motion along a straight line, circular or oscillatory motion:

1. Motion of your hands while running.

2. Motion of a horse pulling a cart on a straight road.

3. Motion of a child in a merry-go-round.

4. Motion of a child on a see-saw.

5. Motion of the hammer of an electric bell.

6. Motion of a train on a straight bridge.

1. Motion of your hands while running – Oscillatory motion.

This motion takes place when the restoring force acting on the body is directly proportional to its displacement from its equilibrium position.

1. Motion of a horse pulling a cart on a straight road – Straight line motion.

Linear motion is a one dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension.

1. Motion of a child in a merry-go-round – Circular motion.

Circular motion is a movement of an object along the circumference of a circle or rotation along a circular path.

1. Motion of a child on a see-saw – Oscillatory motion.

1. Motion of the hammer of an electric bell – Oscillatory motion.

1. Motion of a train on a straight bridge – Straight line motion.

Question 2:

Which of the following are not correct?

1. The basic unit of time is second.

2. Every object moves with a constant speed.

3. Distances between two cities are measured in kilometers.

4. The time period of a given pendulum is not constant.

5. The speed of a train is expressed in.

1. The basic unit of time is second – Correct

2. Every object moves with a constant speed - Not correct

3. Distances between two cities are measured in kilometers – Correct

4. The time period of a given pendulum is not constant - Not correct

5. The speed of a train is expressed in - Not correct

Question 3:

A simple pendulum takes to complete. What is the time period of the pendulum?