# Physics

a 55 kg skateboarder starts out with a speed of 1.8 m/s. he does +80 J of work on himself by pushing with his feet against the ground. in addition, the friction does -265 J of work on him. in both cases, the forces doing the work are nonconservative. the final speed of the skateboarder is 6 m/s. Calculate the change in the gravitational potential energy. How much has the vertical height of the skater changed, and is the skater above or below the starting point?

1. 👍 0
2. 👎 0
3. 👁 633
1. Initial total energy-friction force=final energy.

Let the final energy be KE only, set PE to zero, after all, that point is arbritary.

1/2 m 1.8^2+mgh-frictionwork=1/2 m 6^2
solve for h

1/2 m 1.8^2-265=1/2 m*26

solve for h. If h is negative, then the skater is above the starting point.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### physics

A skateboarder starts from rest at the top and skates down a slope as shown. After 2.5 seconds, the skateboarder has reaches a speed of 10 metres per second. What is the skateboarder's acceleration?

asked by Kirsty Williams on February 25, 2013
2. ### Physics

A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work

asked by Anonymous on November 12, 2012
3. ### physics

A skateboarder starts up a 1.30m high, 25.0° ramp at a speed of 6.70m/s. The skateboard wheels roll without friction. How far from the end of the ramp does the skateboarder touch down?

asked by Anonymous on May 12, 2015
4. ### physics

A 54.5 kg. skateboarder starts out with a speed of 1.90 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the

asked by s on November 21, 2011
5. ### Physics

Consider a skateboarder who starts from rest at the top of a 14.6 m-long ramp that is inclined at an angle of 13.0° to the horizontal. Assuming that the skateboarder's acceleration is g sin 13.0°, find his speed when he reaches

asked by Fallon on September 2, 2010
6. ### physics

A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work

asked by Anonymous on November 11, 2012
7. ### Physics

A 57.5-kg skateboarder starts out with a speed of 1.80 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work

asked by Anonymous on November 17, 2012
8. ### PHYSICS

A 60.8-kg skateboarder starts out with a speed of 1.84 m/s. He does 90.8 J of work on himself by pushing with his feet against the ground. In addition, friction does -278 J of work on him. In both cases, the forces doing the work

asked by KS on April 22, 2015

A 60.8-kg skateboarder starts out with a speed of 1.84 m/s. He does 90.8 J of work on himself by pushing with his feet against the ground. In addition, friction does -278 J of work on him. In both cases, the forces doing the work

asked by KS on April 22, 2015
10. ### physics

A 64.2-kg skateboarder starts out with a speed of 2.21 m/s. He does 98.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -276 J of work on him. In both cases, the forces doing the work

asked by Tyler on January 12, 2017