Question

A body thrown vertically upwards rises to a height of 20m. Calculate the velocity with which the body was thrown upwards and the time taken by the body to reach the highest point.

Answer 1

Answer:

A body thrown vertically upwards rises to a height of 20m.

• The velocity with which the body was thrown upwards will be $20\ m/s$

• The time taken by the body to reach the highest point will be $2\ s$

Explanation:

We can use the first and third equation of motion to solve this question.

Which are given by,

$v = u+at$                           ...(1)

$v^{2} - u^2 = 2as$                     ...(2)

where

u -  initial velocity

v -  Final velocity

a - Acceleration due to gravity

t -  Time

s - displacement of the object

From the question,

$v= 0$           $s = 20\ m$

we know,

$a = -g = -10\ m/s^{2}$

Substitute these values into equation (2)

$0^{2} - u^2 = 2\times-10\times20$

$u^2 = 400$

$u = \sqrt{400} = 20\ m/s$

Thus the velocity with which the body was thrown is $20\ m/s$

Substitute the value of u, v, and a in equation (1) for calculating t.

$0 = 20 - 10t$

$20 = 10t$

$t = \frac{20}{10} = 2\ s$