Calculating Work Done by Forces on a Moving Object

In summary, a person is pushing a 16.0kg shopping cart at a constant velocity for 22.0m at an angle of 29 degrees below the horizontal. There is a 48.0N frictional force opposing the motion of the cart. The magnitude of the force the shopper exerts on the cart is unknown. The work done by the pushing force, the frictional force, and the gravitational force needs to be determined. Using the equation W=(Fcosθ)d and considering the constant velocity, it can be concluded that the net force is zero. However, this does not make sense since the cart is moving forward. Therefore, there must be a force greater than the opposing frictional force.
  • #1
alex7298
27
0

Homework Statement



A oerson pushes a 16.0kg shopping cart at a constant velocity for 22.0m at an angle of 29 degrees below the horizontal. A 48.0N frictional force opposes the motion of the cart.
a)what is the magnitude of the force the shopper exerts on the cart.
Determine the work done by b) the pushing force, c) the fricitonal force, and d) the gravitational force

Homework Equations



W=(Fcostheta)d
W=Fd


The Attempt at a Solution


well I am not sure where to start because using the equation W=(Fcostheta)d leaves you with two variables.
any help would be appreciated
 
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  • #2
Well, what does that constant velocity tell you about total force?
 
  • #3
F=ma
so the net force would be zero, which doesn't make sense becuase the cart is going forward, so wouldn't there have to be a force greater than the one that opposes it?
 

1. What is "work done by a constant force"?

The work done by a constant force is the product of the magnitude of the force and the displacement of the object in the direction of the force. It represents the amount of energy transferred to or from an object by the force.

2. How is the work done by a constant force calculated?

The work done by a constant force can be calculated by multiplying the magnitude of the force by the displacement of the object in the direction of the force, and then taking the cosine of the angle between the force and displacement vectors. This can be represented by the equation W = F · d · cosθ, where W is the work done, F is the force, d is the displacement, and θ is the angle between the force and displacement vectors.

3. What are some examples of work done by a constant force?

Some examples of work done by a constant force include pushing a box across the floor, lifting a book off a table, or pulling a wagon along a sidewalk. In all of these cases, a force is applied to an object and the object moves in the direction of the force.

4. Can the work done by a constant force be negative?

Yes, the work done by a constant force can be negative. This occurs when the force and displacement are in opposite directions, meaning the force is acting against the motion of the object. This results in a negative value for work, indicating that the force is actually removing energy from the object.

5. What is the relationship between work done by a constant force and energy?

The work done by a constant force is directly related to the change in energy of an object. If the force acts in the same direction as the displacement, the work done will be positive and the object will gain energy. If the force acts in the opposite direction of the displacement, the work done will be negative and the object will lose energy. This relationship is represented by the work-energy theorem, which states that the net work done on an object is equal to the change in the object's kinetic energy.

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