A cart of mass M rolls on frictionless bearings and is fitted with a device that launches metal spheres to the left. Any number of metal spheres can be loaded into the top of the launching device, but the device only launches one sphere every T seconds. The device launches all metal spheres with a speed v0 relative to the cart before the sphere is launched. Suppose that the cart has the same mass as a single sphere, that the cart is initially at rest, and that the can loaded with three spheres. The spheres are launched at times t = 1.1=27. and 1= 37. The cart begins moving to the right as a result of the launching of the spheres.

Required:
Sketch a graph of the rightward speed of the cart as a function of time.