How would you go about solving this Work-kinetic energy thorem?

  • Thread starter Merlan114
  • Start date
  • Tags
    Energy
In summary, the conversation discusses a car starting from rest at the top of a driveway with a 20 degree slope. The car is impeded by a friction force of 4.0x10^3N and reaches a speed of 3.8m/s at the bottom of the driveway. The length of the driveway is being calculated using the equation .5mv^2=gmD(cos20), but the answer obtained is different from the given answer of 5.1. The issue may be due to using the wrong formula or not considering the friction force already along the slope.
  • #1
Merlan114
6
0
A 2.1x10^3kg car starts from rest at the top of a driveway that is sloped at an angle of 20 degrees with the horizontal. An average friction force of 4.0x10^3N impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8m/s. What is the length of the driveway?
What i did was:
.5mv^2=gmD(cos20)
.5(2.1x10^3)(3.8)^2=4.0x10^3d(cos 20) and got d= 7.1
I check the back of y book and the answer is 5.1. What did I do wrong? Did I use the wrong formula? How do I go about solving this problem?
 
Physics news on Phys.org
  • #2
That frictional force is already along the slope, so the total energy mgh will be equal to the work done by the frictional force + ke at the bottom of the incline.
 

FAQ: How would you go about solving this Work-kinetic energy thorem?

1. What is the Work-Kinetic Energy Theorem?

The Work-Kinetic Energy Theorem states that the work done on an object by the net force acting on it is equal to the change in the object's kinetic energy. In simpler terms, it explains the relationship between work and kinetic energy.

2. How would you apply the Work-Kinetic Energy Theorem to solve a problem?

To solve a problem using the Work-Kinetic Energy Theorem, you would need to first identify the forces acting on the object and their respective magnitudes and directions. Then, you would calculate the work done by each force and add them together to find the total work done. Finally, you would use the equation KE = 1/2mv^2 to find the final kinetic energy of the object.

3. What are the units for work and kinetic energy?

The units for work are Joules (J) and the units for kinetic energy are also Joules (J). This is because both work and kinetic energy are forms of energy, which is measured in Joules.

4. Can the Work-Kinetic Energy Theorem be applied to all types of motion?

Yes, the Work-Kinetic Energy Theorem can be applied to all types of motion, including linear, rotational, and combined motion. As long as there is a net force acting on the object, the theorem can be used to calculate the work and kinetic energy involved.

5. How is the Work-Kinetic Energy Theorem related to the law of conservation of energy?

The Work-Kinetic Energy Theorem is related to the law of conservation of energy because it helps us understand how energy is conserved in a system. The theorem states that the work done on an object is equal to the change in its kinetic energy, which means that energy is neither created nor destroyed but only transferred from one form to another. This is in line with the law of conservation of energy, which states that the total energy in a closed system remains constant.

Similar threads

Work and kinetic theorem problem using friction
Replies
8
Views
23K
Calculating the Length of a Driveway Using the Work-Kinetic Energy Theorem
Replies
5
Views
3K
Finding length of driveway (work-kinetic energy theorem)
Replies
4
Views
14K
Homework Help: Work-Kinetic Energy Theorem
Replies
3
Views
3K
Work-Kinetic Energy Theorem problem
Replies
2
Views
3K
How Do You Calculate the Speed of a Car Down an Inclined Driveway with Friction?
Replies
6
Views
3K
Questions Regarding a Cat Going Up a Ramp
2
Replies
56
Views
2K
Work-Kinetic Energy Theorum Problem
Replies
3
Views
8K
Solving a 2.1x10^3 kg Car Motion Problem
Replies
4
Views
4K
Conservation of Energy - Friction - Inclined Slope
Replies
6
Views
6K

Hot Threads

Recent Insights

Back
Top