Asked by Uwais
A car accelerates in the +x direction from rest with a constant acceleration of a1 = 1.76 m/s2 for t1 = 20 s. At that point the driver notices a tree limb that has fallen on the road and brakes hard for t2 = 5 s with a constant acceleration of a2 = -5.93 m/s2.
Write an expression for the car's speed just before the driver begins braking, v1.
If the limb is on the road at a distance of 550 meters from where the car began its initial acceleration, will the car hit the limb?
Write an expression for the car's speed just before the driver begins braking, v1.
If the limb is on the road at a distance of 550 meters from where the car began its initial acceleration, will the car hit the limb?
Answers
Answered by
Henry
V1 = a1*t1 = 1.76 * 20 = 35.2 m/s.
d1 = 0.5a1*t1^2 = 0.88*20^2 =
V2 = V1 + a*t = 35.2 - 5.93*5 = 5.55 m/s. The 5-second deceleration is not enough to bring the car to a full stop.
d2 = V1*t + 0.5a*t^2.
d2 = 35.2*5 - 0.5*5.93*5^2 =
d = d1+d2 =
d1 = 0.5a1*t1^2 = 0.88*20^2 =
V2 = V1 + a*t = 35.2 - 5.93*5 = 5.55 m/s. The 5-second deceleration is not enough to bring the car to a full stop.
d2 = V1*t + 0.5a*t^2.
d2 = 35.2*5 - 0.5*5.93*5^2 =
d = d1+d2 =