Posted by **P** on Wednesday, December 5, 2012 at 10:44am.

A 64.4-kg skateboarder starts out with a speed of 2.11 m/s. He does 81.6 J of work on himself by pushing with his feet against the ground. In addition, friction does -289 J of work on him. In both cases, the forces doing the work are non-conservative. The final speed of the skateboarder is 8.56 m/s. (a) Calculate the change (PEf - PE0) in the gravitational potential energy. (b) How much has the vertical height of the skater changed? Give the absolute value.

- Physics -
**Che. It's yur boi!**, Monday, November 30, 2015 at 6:27pm
ΔKE=1/2mvf^2- 1/2mv0^2

a)Plug numbers in

1. ΔKE=1/2(64.4)(8.56)^2- 1/2(64.4)(2.11)^2= -2216.05 (because displacement, I think)

2. -2216.05J+(-289J)-80J

Answer =-2425.05J

b.)

1. W=ΔKE, W=ΔPE(PE=mgh), ΔPE=ΔKE

(64.4kg)(9.8m/s^2)h=2425.05J

631.12h=2425.05J

Answer h=3.842m

Hope this Help

MONEY CASH FLOW

Check out the Rap Channel, Urban Intensity, on YOUTUBE!

## Answer This Question

## Related Questions

- Physics - A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +...
- physics - A 54.5 kg. skateboarder starts out with a speed of 1.90 m/s. He does +...
- Physics - A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +...
- physics - A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +...
- PHYSICS - A 60.8-kg skateboarder starts out with a speed of 1.84 m/s. He does 90...
- PHYSICS PLEASE HELP - A 60.8-kg skateboarder starts out with a speed of 1.84 m/s...
- physics 1 - A 64.4-kg skateboarder starts out with a speed of 1.95 m/s. He does ...
- Physics - a 55 kg skateboarder starts out with a speed of 1.8 m/s. he does +80 J...
- physics - A 54.5-kg skateboarder starts out with a speed of 1.95 m/s. He does +...
- PLEASE HELP - A 60.8-kg skateboarder starts out with a speed of 1.84 m/s. He ...

More Related Questions