# Physics - conservative and non conservative (check

If a sled reaches the base of the hill with a speed of 15.6m/s, how much work was done by the snow on the sled between points x and y, where x is 3m above the ground with a velocity of 14.30m/s and y is toughing the ground. the sled and the rider are 70kg

Ans: i tried the formula work done = Ek+Ep, where Ek =(0.5)(70)(15.60)^2 and Ep= (70)(9.81)(2) i get 7157j which is incorrect, where am i going wrong?

1. 👍 0
2. 👎 0
3. 👁 193
1. Hmmm. It has an initial PE, and an initial KE. Then at the bottom it has only KE. So you want to find the work done on friction.

Initial energy-frictionwork=final energy

friction work= initial energy-finalenergy
= 1/2m(14.3^2)+mg*2 - 1/2 m (15.6^2)

1. 👍 0
2. 👎 0
2. Epot=mgh = (70)(9.81)(3)=2060,1
Ek1 =(0.5)(70)(14.30)^2= 7157,15
Ek2 =(0.5)(70)(15.60)^2=8517,6

total energy= (Epot+Ek1)- Ek2
=9217,25-8517,6
=699,65

1. 👍 0
2. 👎 0
posted by bark
3. I object to your use of "total energy". Your formula expression is the same as mine, but I found the work done on friction. That is not, nor even close to, total energy. So I am not certain what you mean. You found friction work. I also object to the number of significant digits, carrying these calculations to 5 or 6 places is lubricious. You also should use units, the final answer is in Joules (J). I did not check your calculator work.

1. 👍 0
2. 👎 0
4. i agree with you but is the result correct, my english is'nt ok i know

i forgot the units, but sure it is joule

1. 👍 0
2. 👎 0
posted by bark

## Similar Questions

1. ### physics

a sled weighing 100 pounds reaches the foot of a hill with a speed of 40 feet/sec. The coefficient of kinetic friction between the sled and the horizon surface of the ice at the foot of the hill is 0.030. How far will the sled

asked by leonardo magdayo on January 18, 2012

a sled weighing 100 pounds reaches the foot of a hill with a speed of 40 feet/sec. The coefficient of kinetic friction between the sled and the horizon surface of the ice at the foot of the hill is 0.030. How far will the sled

3. ### physics

A 30kg sled(with rider) slides without friction down a small, ice covered hill. On the first run the sled starts from rest and its speed at the bottom of the hill is 8.50m/s. On the second run the sled starts with a speed of

asked by Shakedown78 on November 29, 2015
4. ### Physics

A skier is traveling at a speed of 36.2 m/s when she reaches the base of a frictionless ski hill. This hill makes an angle of 15° with the horizontal. She then coasts up the hill as far as possible. What height (measured

asked by Lily on October 19, 2012
5. ### College Physics

A skier is traveling at a speed of 39.7 m/s when she reaches the base of a frictionless ski hill. This hill makes an angle of 14° with the horizontal. She then coasts up the hill as far as possible. What height (measured

asked by Shannon on October 13, 2014
6. ### Physics URGENT!!!

Gayle runs at a speed of 9.00 m/s and dives on a sled, initially at rest on the top of a frictionless, snow-covered hill, that has a vertical drop of 20.0 m. After she has descended a vertical distance of 4.00 m, her brother, who

asked by Anonymous on October 15, 2012
7. ### PHYSICS

Jamal pulls a 150-N sled up a 28.0 degrees slope at constant speed by a force of 100 N. Near the top of the hill he releases the sled. With what acceleration does the sled go down the hill?

asked by Meme on October 3, 2013
8. ### physics

A child on a sled (total mass 41 kg) slides down a hill inclined at an angle θ = 22° at a constant speed 3.5 m/s. (a) How long does it take the child to travel 40 meters down the slope? (b) What is the frictional force on the

asked by Manny on September 18, 2015
9. ### physics

A sled slides without friction down a small, ice-covered hill. If the sled starts from rest at the top of the hill, its speed at the bottom is 7.60 m/s. What is the height of the hill?

asked by uknown person on December 4, 2017
10. ### physics

a sled slides down a frictionless hill. if the sled starts from rest at the top, its speed is 7.5 m/s. a.) on a second run , the sled starts with a speed of 1.5 m/s at the top.. will it end with less than 9 m/s, 9 m/s, or more

asked by tanya on December 2, 2009

More Similar Questions