Motion Class 9 Notes: Numericals with Answer

Motion is a change in position of an object with respect to time. It can be described using different parameters such as distance, displacement, speed, velocity, and acceleration. Here are some numerical problems related to motion:

Problem 1: A car travels a distance of 50 km in 2 hours. Calculate its average speed.

Solution:

Average speed = Total distance / Total time

= 50 km / 2 hours

= 25 km/hour

Problem 2: A train covers a distance of 360 km in 4 hours. Calculate its average speed in m/s.

Solution:

Average speed = Total distance / Total time

= 360 km / 4 hours

= 90 km/hour

= 25 m/s (1 km/hour = 5/18 m/s)

Problem 3: A car covers a distance of 100 m in 5 seconds. Calculate its average speed in km/hour.

Solution:

Average speed = Total distance / Total time

= 100 m / 5 seconds

= 20 m/s

= 72 km/hour (1 m/s = 3.6 km/hour)

Problem 4: A car starts from rest and accelerates uniformly at 2 m/s2. Calculate its speed after 10 seconds.

Solution:

Acceleration = (Final velocity - Initial velocity) / Time

2 m/s2 = (Final velocity - 0 m/s) / 10 seconds

Final velocity = 20 m/s

Problem 5: A car is moving with a speed of 20 m/s when its brakes are applied. It comes to rest in 5 seconds. Calculate its retardation.

Solution:

Retardation = (Final velocity - Initial velocity) / Time

= (0 m/s - 20 m/s) / 5 seconds

= -4 m/s2 (negative sign indicates retardation)

These numerical problems help in understanding the basic concepts of motion such as speed, velocity, and acceleration.

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