Force and Kinetic Energy

In summary, Josie and Charlotte push a 12-kg bag of playground sand on a frictionless surface for a distance of 6 m with a constant force, starting from rest. The final speed of the sand bag is 0.5 m/s, and the magnitude of the force applied is unknown. The equations F=MA and W=Fdelta(r)cos(theta) can be used to solve for the force, but confusing acceleration with velocity may result in an incorrect solution.
  • #1
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Homework Statement



Josie and Charlotte push a 12-kg bag of playground sand for a sandbox on a frictionless, horizontal, wet polyvinyl surface with a constant, horizontal force for a distance of 6 m, starting from rest. If the final speed of the sand bag is 0.5 m/s, what is the magnitude of the force with which they pushed

Homework Equations




F=MA
W=Fdelta(r)cos(theta)

The Attempt at a Solution


since cos0= 1 I thought it was 36 because W/6=F so w/6=12(.5) so how is W not 36. I'm obnviously forgetting a crucial step but don't understand where. Any help would be great, Thanks a lot.
 
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  • #2
Looks like you are using the idea that the work done equals the kinetic energy acquired.
That would be F*d = 1/2*m*v^2 and it should work well!

In writing F = 12(.5), you are confusing acceleration (unknown) with velocity (.5).
 
  • #3
Alright thanks a lot that makes sense! :)
 

1. What is the difference between force and kinetic energy?

Force is a push or pull on an object, while kinetic energy is the energy an object possesses due to its motion.

2. How are force and kinetic energy related?

Force can cause a change in an object's kinetic energy by either increasing or decreasing its speed or direction of motion.

3. What are some examples of forces that can affect kinetic energy?

Some examples include gravity, friction, and air resistance. For example, gravity can cause an object to accelerate and increase its kinetic energy.

4. How is kinetic energy calculated?

Kinetic energy is calculated by the equation KE = 1/2 * mass * velocity^2, where mass is measured in kilograms and velocity is measured in meters per second.

5. Can kinetic energy be converted into other forms of energy?

Yes, kinetic energy can be converted into other forms of energy, such as potential energy or thermal energy. For example, when a moving object hits a stationary object, its kinetic energy is converted into sound and heat energy upon impact.

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