How does a rotating wheel apply torque/force on a ball?

This direction is constantly changing as the ball moves along the wheel and therefore, the ball is accelerated.In summary, a baseball pitching machine uses a rotating wheel to accelerate the ball and send it flying at an appropriate angle. The wheel rotates faster than the ball, causing friction that accelerates the ball in a tangential direction. This allows for the transfer of energy from the wheel to the ball, resulting in the ball being launched in a straight line.
  • #1
Stolbik
2
0
I saw a baseball pitching machine that throws baseballs at 40-70mph with one wheel... All that wheel does is rotate and as the ball touches the rotating wheel it accelerates and comes flying out of the machine at an appropriate angle.. My question is: what is the physics behind that wheel on ball action? I understand torque but I don't get how it works since the ball is "parallel" to the wheel. There is nothing pushing the ball in a straight line... How is the energy transferred from wheel to ball? Thanks!
 
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  • #2
The wheel moves quicker than the ball, and friction will accelerate the ball. The precise direction is not so important - after leaving the machine, the ball will always fly in a straight line (at least if we neglect gravity and air resistance), and if the direction does not fit, simply rotate the machine.
 
  • #3
there is friction between the ball and the wheel. It makes the ball move in the direction tangential to the point on the wheel where the ball makes contact.
 

1. How does a rotating wheel apply torque on a ball?

When a wheel is rotating, it has a certain angular velocity and angular momentum. This angular momentum is transferred to the ball through frictional forces between the wheel and the ball. As the ball moves along with the rotating wheel, it experiences a change in its angular velocity, resulting in a torque or twisting force being applied to it.

2. What is the relationship between the speed of rotation and the torque applied on the ball?

The torque applied on the ball is directly proportional to the speed of rotation of the wheel. This means that as the wheel spins faster, the ball experiences a greater torque, resulting in a greater force being applied on it.

3. How does the shape and size of the wheel affect the torque applied on the ball?

The shape and size of the wheel can affect the torque applied on the ball in two ways. Firstly, a larger wheel will have a larger radius, resulting in a greater distance between the point of rotation and the point of contact with the ball. This increases the leverage and therefore the torque applied on the ball. Secondly, the shape of the wheel can affect the distribution of mass, which can also impact the torque applied on the ball.

4. Does the mass of the ball have an impact on the torque applied by the rotating wheel?

Yes, the mass of the ball does have an impact on the torque applied by the rotating wheel. This is because the mass of the ball affects its inertia, which is the resistance to changes in its state of motion. The greater the inertia, the more force is required to change the ball's angular velocity, resulting in a greater torque being applied.

5. Can the direction of the torque on the ball be changed?

Yes, the direction of the torque on the ball can be changed by changing the direction of rotation of the wheel. For example, if the wheel is rotating clockwise, the torque on the ball will be in one direction. But if the wheel is rotated counterclockwise, the torque on the ball will be in the opposite direction.

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