100POINTS!!!
The force of the ruler on the ball is called an applied force. The force of the barrier on the ball is called a normal force. Both of these forces are exerted by surfaces, and the direction of force is at a right angle to the surface. The difference is that an applied force is exerted by a moving object and a normal force is exerted by a stationary object. Draw two arrows to represent the applied force and the normal force on the ball.