Sarah and her bicycle have a total mass of 40 kg. Her speed at the top of a 10 m high and 100m long hill is 5 m/s. If the force of friction on her way down is 20 N, at what speed will she be going when she reaches the bottom

She will be going at 11.01 m/s when she reaches the bottom.      

Explanation:

We can find the speed at the bottom by equating the total work with the change in energy:

  (1)

There is no energy conservation because there is a force of friction on her way down.  

By entering , where is the force of friction (is negative because it is in the opposite direction of motion) and d is the displacement, into equation (1) we have:

In the initial state, we have kinetic and potential energy and in the final state, we have only kinetic energy.

Where:

m: is the total mass = 40 kg

: is the final speed =?

: is the intial speed = 5 m/s

g: is the gravity = 9.81 m/s²

h: is the height = 10 m

By solving the above equation for we have:

Therefore, she will be going at 11.01 m/s when she reaches the bottom.                                    

I hope it helps you!                      

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement