Double Checking a Bicycle Downhill Homework Problem

[Aikenfan]

Homework Statement

I wasn't sure if i was doing this problem correctly, if anyone could double check for me, that would be great!
You ride your bicycle down a hill. Your total mass is 40 kg. At the top of the hill, your
speed is 5 m/s. The hill is 20 m high and 200 m long. If the force of friction is 20 N, what is
your speed at the bottom of the hill?

Homework Equations

The Attempt at a Solution

Top =
KE = 1/2 m v ^2
KE = 1/2 (40) (5)^2 = 500

PE = mgh
(40) (9.8) (20) = 7840

W = Fd
(20)(200)= 4000

7840 - 4000
=3840

3840 + 500 = 4340 = 1/2 (40) v ^2
divide both sides by 20
take the square root, and got 14.7 as my answer...

 

[Dick]

Looks ok to me. Though I'd be more careful about putting units on things.

 

[m2003]

I would suggest double checking your calculations and equations to ensure accuracy. It is always a good practice to review your work and make sure all the steps are correct. Additionally, it would be helpful to provide more context for the problem, such as the direction of motion and any other forces acting on the bicycle, in order to fully understand the situation and provide an accurate solution. It may also be beneficial to break down the problem into smaller components and use relevant equations, such as the work-energy theorem, to solve for the final velocity at the bottom of the hill. Overall, it is important to be thorough and precise in solving scientific problems to ensure accurate results.