Question

Question #5304e

Answer 1

`3.57` meters

Explanation:

`E_P=mgh`

Where `E_P` is the potential energy
`m` is mass in kilograms
`g` is the acceleration of gravity on Earth
`h` is the height above ground (reference point)

Using the units given, you can identify that you have the mass and potential energy, and need height. Plug these numbers into the formula.

`70J=2kg*9.8m/s^2*h`

Simplifying the right-hand side gives `70J=19.6(kg*m)/s^2*h`

Divide both sides by 19.6 kilograms meters per second squared on both sides of the equation to get the height.

`3.57m=h`

Answer 2

`3.57m` (or `3.5m`)

Explanation:

`GPE = mgh`

where `m` is mass, in `kg`
`g` is gravitational field strength, in `N//kg`
`h` is height, in `m`.

`h = (GPE)/(mg)`

`m = 2kg`
`g ~~ 9.81` (assuming that the question is set on Earth)
`GPE = 70J`

`(GPE)/(mg) = 70/(2*9.81)`

`=70/19.62`

`h = 70/19.62`

`= 3.57m` (3s.f.)

note: if you want to use `10N//kg` for the value of `g`, the method is the same. the answer obtained is `7/2`, which is `3.5m`.