Question

A device is needed to accelerate a 3000 lb vehicle into a barrier with constant velocity to test its 5 mph bumpers. The vehicle will start at rest, move forward, and have constant velocity for the last part of its motion before striking the barrier with the specified velocity.
Design a cam-follower system to do this. The vehicle will leave contact with your follower just prior to the crash.

Answer 1

Answer:

The cam-follower system is designed such that the vehicle will move at a speed, v = $\frac{Fgt}{W}$

Explanation:

The vehicle starts at rest, u = 0 m/s

Some force, F, will be applied by the device on the truck

The force is given by the equation, F = ma

a = F/m..........(1)

The weight of the vehicle is given by W = mg

m = W/g.........(2)

Substituting equation (2) into (1)

a = F ÷ (W/g)

a = gF/W............(3)

The applied force makes the vehicle to move with constant velocity, v

From the equation of motion, v = u + at............(4)

v = 0 + (gF/W)t

v = $\frac{Fgt}{W}$

Answer 2

Answer:

The device acceleration is

a = f/m = f/(w/g)=fg/w

The velocity v is

v= u +at

When u =o

v = at

Substitute the value of a

v = fgt/w