Velocity can change due to change in ___.

Velocity can change when there is a change in speed or direction or both. Hence, option 4 is correct.

A and B decided to row a boat which was at rest in the river bank. First A took the charge and rowed the boat with a velocity of 10 m/s for 40 seconds. Then B decided to him and together they rowed the boat at 20 m/s for 30 seconds. When do you think the acceleration was more?

When A rowed the boat, initial velocity = 0 final velocity = 10m/s Time = 40 seconds acceleration = (10 − 0)/ 40 = 0.25 m/s² When A and B are rowing together, initial velocity = 10m/s final velocity = 20m/s Time = 30 seconds acceleration = (20 − 10)/ 30 = 0.33 m/s²

Meera swimmed from one end of a swimming pool to another and then returned back. The pool is 200 meter long and time taken by Meera is 5 minutes. Calculate average speed and average velocity of Meera.

Total Distance = 200 + 200 = 400 meter Time taken = 5 minutes = 5 × 60= 300 seconds Displacement in 5 minutes = 0 m Average speed = 400/300 = 1.33 m/s Average velocity = displacement/ Time = 0/ 5 = 0 m/s

Calculate acceleration if a car covers a distance of 200 m with an uniform velocity of 40 m/s in 5 seconds.

The vehicle is in uniform velocity, so it does not accelerate. Hence, option 4 is correct

Which physical quantity is measured in distance/second²?

Velocity and speed are measured in distance/second, so option 1, 2 & 4 are not possible. Acceleration is measured in distance/second² Hence, option 3 is correct.

A is driving a car at the speed of 10m/s. After 4 seconds the car comes to rest as brakes are applied. What will be the acceleration and retardation of the vehicle?

Initial speed = 10 m/s Final speed = 0 m/s Time = 4 seconds Acceleration = (0 − 10)/ 4 = −2.5m/s² Retardation = 2.5m/s²