# Kinetic Energy, Work Done, and Inclines

• orbits
In summary, the UPS delivery man loads his truck by pushing parcels up a 30-degree inclined ramp. The kinetic friction acting on a 15 kg parcel is 12.99 N. To give the parcel an initial kinetic energy of 75 J, the man must do work on it by pushing it a short distance of 0.75 m with an average force of 86.68 N, ignoring friction.
orbits
UPS delivery man is loading his truck by shoving the parcels up a ramp. The ramp is inclined at an angle of 30 degrees above the horizontal. He sends a parcel of mass 15 kg, up this ramp. the coefficient of sliding friction is .10 and gravitational force is class standard (10).

A The magnitude of the kinetic friction acting on the parcel is?
B He sends parcel up ramp with initial Kinetic Energy, E, so that by the time, the parcels up the ramp, it has 0 KE. Ramp is length 1.0m.
C To give this parcel this initial KE, he most do WORK on the parcel. Assuming he pushed it a short distance of .75m what is the average force he needs to apply. Ignore friction for this part.

The work I have done is:

A
Y Components: N-MG Cos 30 --> N=150 Cos 30 --> N=129.9
Friction = $$\mu$$k * N --> .10 * 129.9 ---> Magnitude =12.99

B

1/2 M Vo2+ [STRIKE]MGH[/STRIKE]= [STRIKE]1/2 M Vf2[/STRIKE] + MGH

1/2 M Vo2 = MGH

H= Sin30 -->.5

1/2 (15) (V)2= 75
V=3.16

So initial KE = 75 ?

C

Is related to B so if that's wrong this is wrong.

Work = Force * Displacement
Work = KE

KE: 75 / Disp: .75 = Force: 100N

Part a looks fine. Part B is missing the effects of frictional dissipation which will rob some of the PE.

C is done by ignoring friction but asks that you compute force from the work done and the displacement over which force is appplied. Assuming he pushes parallel to the ramp--this will be F*d=energy required to get to top. That help?

So for B:

Energy - Friction= 75-12.99 = 62.01For C:

Would I use the new energy 62.01/ (.75) = 86.68N

## 1. What is kinetic energy and how is it calculated?

Kinetic energy is the energy an object possesses due to its motion. It is calculated by using the formula KE = 1/2 * mass * velocity^2.

## 2. How is work done related to kinetic energy?

Work done is the transfer of energy from one object to another. When a force acts on an object and causes it to move, work is being done and this increases the object's kinetic energy.

## 3. Can kinetic energy be negative?

No, kinetic energy is always a positive value. This is because both mass and velocity are squared in the calculation, resulting in a positive value even if the object is moving in the opposite direction.

## 4. How does an incline affect the work done and kinetic energy of an object?

An incline can affect the amount of work done and kinetic energy of an object by changing the direction and magnitude of the force acting on the object. If an object is moving up an incline, more work is required to overcome the force of gravity, thus increasing its kinetic energy. If an object is moving down an incline, less work is required and its kinetic energy decreases.

## 5. How is potential energy related to kinetic energy on an incline?

Potential energy is the energy an object possesses due to its position or state. On an incline, an object has potential energy due to its height above the ground. As the object moves down the incline, its potential energy decreases and its kinetic energy increases. At the bottom of the incline, all of the potential energy is converted into kinetic energy.

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