A brick of mass M has been placed on a rubber cushion of mass m. Together they are sliding to the right at constant velocity on an ice-covered parking lot. (a) Draw a free-body diagram of the brick and identify each force acting on it. (b) Draw a free-body diagram of the cushion and identify each force acting on it. (c) Identify all of the action–reaction pairs of forces in the brick–cushion–planet system.

A block of mass

M

has been placed on a rubber cushion of mass

m

The rubber cushion and block together slides to the right at constant velocity on an ice covered parking slot.

Acceleration due to gravity

g

Part a )

Free body diagram of the brick on the rubber cushion.

FBD of the brick

FBD of the brick

The brick is at rest with respect to the rubber cushion.

The only forces acting on it is the reaction force N from the rubber cushion in response to the weight Mg exerted on the cushion.

Part b)

Free body diagram of the cushion

FBD of the cushion

FBD of the cushion

The cushion is moving at constant velocity in a friction free area. So no force is acting in the direction of motion or opposite to it.

The forces acting on the cushion are the weight

Mg

of the brick and the reaction force from the parking ground

N1=(M+m)×g

Part c)

1 ) Brick Cushion system - the weight of the brick

Mg

acting on the cushion and reaction from the cushion

N=Mg

acting on the brick.

2) Brick cushion planet system - the weight of the brick and cushion

(M+m)×g

acting on the planet and reaction force from the planetN1=

(M+m)×g

acting on the cushion.

HOPE IT HELPS