Question #1) For a 1,505-kg car with a drag constant D=0.49 kg/m, which is movin
ID: 1318988 • Letter: Q
Question
Question #1) For a 1,505-kg car with a drag constant D=0.49 kg/m, which is moving at a speed of 40 mph, what is the magnitude of the maximum acceleration (right at this speed) at which the car can be slowed down. The coeffcicient of kinetic friction is 0.63 and the coefficient of static friction is 0.84.
Question #2) For a 1,524-kg car with a drag constant D=0.47 kg/m, which is moving at a speed of 40 mph, what is the magnitude of the maximum acceleration (right at this speed) at which the car can further speed up. The coeffcicient of kinetic friction is 0.58 and the coefficient of static friction is 0.82.
Explanation / Answer
1.
40 mph = 17.88 m/s
Fd = D v2
frictional force = muk m g
net force = D v2 + (muk m g)
ma = D v2 + (muk m g)
a = D v2 / m + muk g
= [0.49 / 1505] 17.882 + 0.63 * 9.8
= 6.278 m/s2
2.
39 mph = 17.43 m/s
Fd = D v2
frictional force = muk m g
net force = D v2 + (muk m g)
ma = D v2 + (muk m g)
a = D v2 / m + muk g
= [0.47 / 1524] 17.882 + 0.58 * 9.8
= 5.78 m/s2