Question

A toy rocket weighing 10N blasts from ground level. At the exact top of it's trajectory it's energy is 140J. To what vertical height does it rise?

Answer 1

Given that a toy rocket weighs10N.

If i its mass be `m`kg then `mg=10N`, where acceleration due to gravity `g=9.8ms^-2`

Now it is also given that at the exact top of it's trajectory it's energy is 140J. At the exact top of its trajectory it will have only gravitational potential energy considering only the vertical motion of the rocket.

If the rocket reaches `H` m at the top, then

Its PE at the top `mxxgxxH=140`

So `H=140/(mg)=140/10=14`m