# physical sciences

You throw a 0.5kg rock directly upwards with a speed of 7ms−1. If all the kinetic energy becomes gravitational potential energy, how high will the stone go?

Original post by raffay13
You throw a 0.5kg rock directly upwards with a speed of 7ms−1. If all the kinetic energy becomes gravitational potential energy, how high will the stone go?

You have a formula for kinetic energy?
You have a formula for potential energy at a height, h?
Equate the two to find h.
You don't actually need the mass of the rock, and can do this purely with a SUVAT equation.
Original post by raffay13
You throw a 0.5kg rock directly upwards with a speed of 7ms−1. If all the kinetic energy becomes gravitational potential energy, how high will the stone go?

mgh=0.5mv^2
Make h subject of formula, u will be fine
Original post by raffay13
You throw a 0.5kg rock directly upwards with a speed of 7ms−1. If all the kinetic energy becomes gravitational potential energy, how high will the stone go?

A rock gets potential energy when it has achieved the highest height of fall and changes to kinetic energy when the rock falls. In mathematical sense it means that kinetic energy is converted to potential energy and vice versa, so you have to equate both formulas to do your calculations!
(edited 2 years ago)
i got the answer of 2.5 is that correct if not can you please help me by doing a step by step calculator to get to the final answer.
Original post by raffay13
i got the answer of 2.5 is that correct if not can you please help me by doing a step by step calculator to get to the final answer.

Looks correct
is that what you got as well. can you check just to make sure please. thanks.
Original post by raffay13
is that what you got as well. can you check just to make sure please. thanks.

Yeah it is correct 2.5m
Original post by raffay13
is that what you got as well. can you check just to make sure please. thanks.

I got the same value. If you have calculated the height h = 1/2*(v²/g) in that way after conversion, it is alright.