Answer to Question #71114 in Mechanics | Relativity for John Citty

Question

A car goes at a constant 16 m/s up a hill. the frictional force is 500N. The height of the hill is .3 km and it the car travels a distance of 4.8 km. What is the work done in order to get to the top of the hill.?

Answer 1

v=16〖ms〗^(-1)
"h\=" 3"km"
"l\=" 4"\." 8"km"
"g\=\1\0" 〖"ms" 〗^(-2)
F=500N
A-?
A work A done by traction force of the car consist of two terms
A=A_1+A_2,
where A_1=mgh - work done against gravity and A_2=F_fr l=500⋅4800=2400(kJ) - work done against frictional force.
To calculate A_1=mgh we need to know a mass mof a car.
Answer: A=2400kJ+mgh