Work energy principle and power

In summary, to find the speed of a box sliding down a smooth ramp with a height of 20cm and a length of 2.5m, we can apply conservation of energy by equating the change in kinetic energy to the loss of gravitational potential energy. By filling in the values for gravity and height, we can solve for the speed, which is approximately 2m/s.
  • #1
Shah 72
MHB
274
0
A box slides down a smooth ramp. The height of the ramp is 20cm and the length of the ramp is 2.5m. The box starts from rest. What is the speed of the box when it reaches the bottom of the ramp?
I don't understand how to solve this. Pls help
 
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  • #2
We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?
 
  • #3
Increase in KE= loss of GPE
1/2mv^2= mgh
So gpe at the top = m×10× 0.2
GPE at the bottom = 0J
 
  • #4
Klaas van Aarsen said:
We can apply conservation of energy.

What is the energy due to gravity at the beginning?
What is the kinetic energy at the end?
I don't understand how to solve this. Pls help
 
  • #5
You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.
 
  • #6
Klaas van Aarsen said:
You have the correct equation.
Fill in g and h.
And we can cancel m from both sides.
h=0.2m, so v= 2m/s. I was getting confused with the length of the ramp.
Thanks a lottt!
 

FAQ: Work energy principle and power

What is the work-energy principle?

The work-energy principle states that the work done on an object is equal to the change in its kinetic energy. This means that when a force acts on an object, it either speeds up or slows down, and the work done by the force is equal to the change in the object's kinetic energy.

How is work calculated?

Work is calculated by multiplying the force applied to an object by the distance the object moves in the direction of the force. The formula for work is W = Fd, where W is work, F is force, and d is distance.

What is the relationship between work and energy?

Work and energy are closely related, as work is the transfer of energy from one object to another. Work is also a measure of the change in an object's energy. When work is done on an object, its energy changes, and when work is done by an object, it loses energy.

What is power?

Power is the rate at which work is done or energy is transferred. It is calculated by dividing the amount of work done by the time it takes to do the work. The unit of power is watts (W), which is equal to one joule per second (J/s).

What are some real-world applications of the work-energy principle and power?

The work-energy principle and power have many real-world applications, such as calculating the power output of a car engine, determining the work done by a weightlifter, and understanding the energy transfer in a roller coaster. They are also important in fields such as engineering, physics, and sports science.

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