Course Home Home Work 8- Microsoft Edge | 811778268offset-next Home Work Problem
ID: 1779482 • Letter: C
Question
Course Home Home Work 8- Microsoft Edge | 811778268offset-next Home Work Problem 7.37 Problem 7.37 Part A A 960-kg sports car collides into the rear end of a 2400-kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8 m before stopping. The police officer estimating the coefficient of kinetic friction between ires and road to be 0.80, calculates the speed of the sports car at impact What was the speed sports car at impact? Express your answer to two significant figures and inc Value Units Submit My Answers Give Up O Type here to search o iDExplanation / Answer
Use the following equation to determine the velocity of two cars immediately after impact.
vf^2 = vi^2 + 2 * a * d, vf = 0 m/s, d = 2.8 m
The friction force causes the cars decelerate. Use the following equation to determine the friction force.
Ff = * Total mass * g = 0.8 * 3360 * 9.8 = 26,342.4 N
Use the following equation to determine the acceleration.
a = Ff ÷ Total mass = 26,342.4 ÷ 3360 = 7.84 m/s^2
Since the cars are decelerating, the acceleration is -7.84
0 = vi^2 + 2 * -7.84 * 2.8
-vi^2 = -43.904
vi = 43.904
This is approximately 6.626 m/s.
Now we can do a conservation of momentum problem to determine the initial speed of the sport’s car.
Initial momentum = 960 * v
Final momentum = 3360 * vi
960 * v = 3360 * 6.626
vi = 23.19 m/s
This is approximately 23 m/s (ans)