Question

A rat jumps in your lap and you scream like a baby and toss it straight upwards in the air. 3 seconds later, it lands back in your lap again. A) at what speed did you throw the rat? B) what is the maximum height reached by the rat?

Answer 1

Total time of flight of rat to go up in the air and again come back on the lap is given as

`T = 3 s`

Part a)

This time of flight depends on the initial speed and acceleration due to gravity

So by kinematics we can say

`T = (2v)/(g)`

`3 = (2v)/(9.8)`

`v = 14.7 m/s`

Now in order to find the maximum height we can use

`v_f^2 - v_i^2 = 2 a d`

here final speed is zero and acceleration is due to gravity

`0 - v^2 = 2*(-g)*H`

by rearranging above equation we have

`H = (v^2)/(2g)`

`H = (14.7^2)/(2*9.8)`

`H = 11.025 m`

so it will move up to height 11.025 m