Question

A car weighting 1500 kgf and with a 200 hp power travels up a slope inclined at 60° with constant speed for 20 s
a) Calculate the change in kinetic energy
b) Calculate the change in potential energy
c) Is mechanical energy conserved? Justify your answer
d) What is the work done by the gravitational force?
e) Calculate the net work on the car

Answer 1

a)

m = mass of the car = 1500 kg

P = power = 200 hp = 200 x 746 = 149140 Watt

t = time = 20 s

Since the speed is constant

v_o = initial speed = v_f = final speed = v

Change in kinetic energy

K = (0.5) m (v_f² - v_o²)

K = (0.5) (1500) (v² - v²)

K = 0 J

b)

Change in potential energy is given as

U = P t

U = (149140) (20)

U = 2982800 J

c)

yes the mechanical energy is conserved

d)

W = work done

W = - U

W = - 2982800 J