Answer:
The required power by the engine is 33.0 hp
Explanation:
Solution
Newton's second law says that, the net force Fnet on an object of mass m will accelerates the object
Where
Fnet = ma
a = acceleration
θ = angle of incline,
m = mass of the 30 skiers,
f = frictional force
N = normal force
mg sinθ, mg cos θ are components of weight skier
F = the force applied by engine
Now,
The skier mass is 65 kg
We calculate the mass of the 30 skier
m = 30 (65kg) = 1950 kg
Calculate the net force acting on the skiers along the x-axis
Fnet, x=ma
Now,
F-mg sin θ - f = 0
F= mg sin θ + f -----(1)
The kinetic frictional force is denoted by
f = μk N ------(2)
μk = The coefficient of the kinetic friction
We now, calculate the net force acting on the skiers along y axis
Fnet, y = ma
N- mg cos θ = 0
so,
N = mg cos θ
This value is substituted in equation (2)
f = μk mg cos θ
we substitute the value for equation (1)
F = mg sin θ + μk mg cos θ
mg = sinθ + μk cos θ)-----(3)
The next step is to calculate the work done by the engine in pulling the skiers, the incline top by applying the equation 3
W = Fx
= mg ( sinθ + μk cos θ)x
x = the displacement
we now substitute 1950 kg for m, 23° for θ, 0.10 for μk and 320m for x
so,
W = mg ( sinθ + μk cos θ)x
= (1950 kg) (9.81 m/s²) (sin 23° + (0.10) cos 23°) (320 m)
= 2.99 * 10 ^6 J
Then,
The time from minute to s is converted
t =(2.0min) ( 60sec/1.0min) = 120 sec
Now we calculate the power needed by the engine to pull the skiers at the incline top
Thus,
P = W/t
we substitute 2.955 * 10 ^6 J for W and 120 s for t
we have,
P = 2.955 * 10 ^ 6 J/ 120 s
= ( 2.4625 * 10 ^ 4 W) (1.0 hp/746 W)
= 33.0 hp
In conclusion the required power by the engine is 33.0 hp
