7. A girl pushes her little brother on his sled with a force of 300. N for 750. m. How much work is this if the force of friction acting on the sled is (a) 200. N. (b) 300. N?

a) 75000Joules

b) 0Joules

Explanation:

Workdone = Force * Distance

Given

distance= 750m

Force = 300N

a) If the frictional force = 200N

The Total force = 300N - 200N = 100N

Work done = 100 * 750

Workdone = 75,000Joules

Hence the workdone if the force of friction is 200N is 75,000Joules

b) If the frictional force = 300N

The Total force = 300N - 300N = 0N

Work done = 0* 750

Workdone = 0Joules

Hence the workdone if the force of friction is 300N is 0Joules i.e no work will be done on the sled

the speed of the cart after 3 seconds of low fan speed is ⇒ 54.0 cm/s.

the speed of the cart after 5 seconds of medium fan speed is ⇒ 120.0 cm/s.

the speed of the cart after 2 seconds of high fan speed is ⇒ 64.0 cm/s. 

just did the lab.