Answer:
work done by friction = 5889 J
Explanation:
We are given;
Mass of car; m = 130 kg
Speed at point A; v1 = 25 m/s
Speed at point B: v2 = 8 m/s
Since radius is 12 m
At point A, distance is; y1 = 12 m
At point B, distance is; y2 = -12 m
Now, formula for work done by all the forces is given by the equation;
Total work;
W_gravity + W_others = K2 - K1
Where W_others is work done by other forces which is equal to work done by friction
Where K2 - K1 is change in kinetic energy.
W_grav is also change in potential energy and is expressed as;
W_grav = mgy1 - mgy2
K2 - K1 = ½m(v1)² - ½m(v2)²
Thus;
mgy1 - mgy2 + W_others = ½m(v1)² - ½m(v2)²
Making W_others the subject;
W_others = ½m(v1)² - ½m(v2)² + mgy2 - mgy1
Plugging in the relevant values;
W_others = (½ × 130 × 25²) - (½ × 130 × 8²) + (130 × 9.8 × -12) - (130 × 9.8 × 12)
W_others = 5889 J
Recall that I earlier said W_others = work done by friction.
Thus, work done by friction = 5889 J