Question

8. a)A body which is thrown upward rises to a height 'h' and comes back
to the position of the start. Calculate
i) the net displacement.
ii) distance travelled by the object.
b) what is retardation ? give an example.
(3)​

Answer 1

Answer :

Given -

• A a body is thrown upward.
• It rises to a height of 'h'
• Then, it come back to the start position.

To Find -

• Net displacement
• Distance travelled

Solution -

As the body rises to a height of h after it is thrown upwards and come back to the starting position, the net displacement of the body will be 0. This is because, the starting position and the end position is almost the same and hence the net displacement between this true is negligible or equal to zero.

As the body is thrown upward at the height of 'h', and then it returns to its starting position, by this we can say that the total distance travelled by the body is 2h.

⇒ What is retardation ?

Retardation is said to be negative acceleration. Acceleration is the rate of change of velocity of the body.

It is a vector quantity as it tells us about the magnitude along with the direction in which the body is moving.

A Negative acceleration or retardation is is acceleration in opposite direction to the motion.

The negative sign in the acceleration/retardation implies the direction of the motion i.e. opposite to the motion.

Example for retardation is : When a vehicle slows down to stop.