word problem

Question

you are on roller blades on the top of a small hill. your potential energy is equal to 1000.0 j. The last time you checked your mass was 60.0 kg.

 

a. what is your Wight in newton's?

 

b. what is the height of the hill.

 

c. If you start skating down the hill, your potential energy will be converted to kinetic energy. At the bottom of the hill , what will be your speed? 

Answer 1

Given:

m = 60 kg

PE = 1000 kg m²/s²

 

 

Part a)

 

Weight = mg

 

mg = (60 kg)(9.81 m/s²)

           = 588.60 kg m/s²

 

Part b)

 

mgh = PE

 

h = PE / mg

h = (1000 kg m²/s²) / (588.60 kg m/s²)

h = 1.699 m

 

Part c

 

Conservation of energy states that  PE + KE = 0

 

KE = -PE   ----> negative sign in front of PE indicates loss of potential energy.

 

(1/2)mv² = PE

 

mv² = 2PE

 

v² = (2PE/m)

v² = (2* 1000 kg m²/s²) / 60 kg

v² = 33.33 m²/s² 

v =√(33.33 m²/s²)

v = 5.77 m/s