Question

How many joules of potential energy does a 1-kg book gain when it is elevated 4 m? What about when it is elevated 8 m?

Answer 1

`40J" "&" "80J`

Explanation:

Gravitational potential energy(GPE)

is calculated by the formula

`GPE=mgh`

where

`m="mass"`

`g=10ms^(-2)`

`h="height from a fixed reference point"`

`GPE_1=1xx10xx4=40J`

`GPE_2=1xx10xx8=80J`

Answer 2

4m - `39.36J~~40J`

8m - `78.72J~~80J`

Explanation:

G.P.E. is given by the fomula `E_(grav)=mgDeltah`, where:
`m` = mass (kg)
`g` = acceleration due to gravity (`9.81ms^(-2)`)
`Deltah` = change in height (`m`)

4m:
`E_(grav)=1*9.81*4=39.36J~~40J`

8m:
`E_(grav)=1*9.81*8=78.72J~~80J`