Work/Energy problem at an angle

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In summary, the question asks how much greater the kinetic energy of a sliding block would have been if a pulling force of 60 N had not been applied. Using the work equation, it is found that without the pulling force, the block's kinetic energy would have been 25.6 J higher. The mistake in the attempt at a solution was using the cosine factor unnecessarily.
  • #1
Heather_
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1. Homework Statement

In the figure below, a block of ice slides down a frictionless ramp at angle θ = 50°, while an ice worker pulls up the ramp (via a rope) with a force of magnitude Fr = 60 N. As the block slides through distance d = 0.65 m along the ramp, its kinetic energy increases by 85 J. How much greater would its kinetic energy have been if the rope had not been attached to the block?

2. Homework Equations
W=ΔEk
W=F*d*cosθ

3. The Attempt at a Solution

First, I solved for the gravitational force in the X direction: (Fgx-60N)*.65m*cos50=85J
Fgx = 263.44 N
Then, I plugged it back into the work equation to see how much work would be done then: 263.44N*.65m*cos50=W
W=110.06J=ΔEk
110.6J-85J=25.6J
Yet, this is not the right answer. What am I doing wrong?
 
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  • #2
Heather_ said:
First, I solved for the gravitational force in the X direction: (Fgx-60N)*.65m*cos50=85J
The x-component of gravity and the 60 N force are already parallel to the ramp, so no need for the cos50 factor.
 
  • #3
Wow. That was a silly mistake. Thank you! :)
 

Related to Work/Energy problem at an angle

What is the Work/Energy problem at an angle?

The Work/Energy problem at an angle is a physics problem that involves calculating the work done on an object that is moving at an angle to the horizontal. It is based on the principles of work and energy, which state that the work done on an object is equal to the change in its kinetic energy.

How do you calculate the work done at an angle?

To calculate the work done at an angle, you will need to use the formula W = Fd cosθ, where W is the work done, F is the force applied, d is the displacement of the object, and θ is the angle between the force and the displacement. This formula takes into account the direction of the force in relation to the direction of the displacement.

What is the difference between work done at an angle and work done in a straight line?

The main difference between work done at an angle and work done in a straight line is that in the former, the force and the displacement are not in the same direction. This means that the force is not directly causing the displacement, and therefore, the work done will be less than the force applied multiplied by the displacement.

Can the work done at an angle be negative?

Yes, the work done at an angle can be negative. This occurs when the force applied is in the opposite direction of the displacement. In this case, the work done will be negative, indicating that the applied force is actually slowing down the object rather than speeding it up.

What are some real-world examples of the Work/Energy problem at an angle?

Some real-world examples of the Work/Energy problem at an angle include pushing or pulling a sled up a hill, lifting a suitcase onto a luggage rack, and pushing a shopping cart at an angle. In all of these situations, the force being applied is not directly in line with the displacement, and therefore, the work done will be calculated using the formula W = Fd cosθ.

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