Question

A 1700-kg truck and a 1000-kg car are parked with their rear bumpers nearly touching each other in a level parking lot. Both vehicles have their brakes off so that they are free to roll. A man sitting on the rear bumper of the truck exerts a constant horizontal force on the rear bumper of the car with his feet, and the car accelerates at 1.2 m/s2. Ignore any friction between the tires and the parking lot surface. The direction of the unit vector ı^ is the direction of motion of the car.

What is the acceleration of the center of mass of the car-truck system?

What is the vector sum of forces exerted on a car?

What is the vector sum of forces exerted on a truck?

What is the acceleration of the truck?

Answer 1

Here,

acceleration, a = 0 m/s^2

as there is no external force acting on the car truck system

the acceleration of the center of mass is Zero

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for the force on the car

Force = 1000 * 1.2 = 1200 N

the net force on the car is 1200 N

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the force on the truck will be opposite to the force acting on the car

the vector sum of forces exerted on a truck = - 1200 N

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acceleration of the truck = -1200/1700

acceleration of the truck = -0.71 m/s^2