Bowling Ball Changing Rotational Direction

In summary, the conversation discusses the role of friction in the motion of a ball and its implications on its rotation and sliding. The participants consider various scenarios, including a frictionless patch on the surface, to understand the behavior of the ball. They also emphasize the importance of reasoning and critical thinking in understanding physics concepts.
  • #1
Curtiss Oakley
23
0
Homework Statement
A uniform bowling ball of radius R, mass M is thrown down a horizontal lane with initial horizontal speed v0 and backspin(as shown below) with initial angular speed ω0, such that v0 > Rω0. So after the ball makes contact with the horizontal lane, it rolls with slipping on the lane. The kinetic frictional force fk acting on the ball causes a center of mass acceleration of the ball acom to slow down its linear motion. Meanwhile this kinetic frictional force fk also produces a torque that causes an angular acceleration of the ball to speed up its angular motion. When speed vcom has decreased enough and the angular speed ω has increased enough, the ball will start to roll without slipping. The coefficient of kinetic friction between the ball and lane surfaces is μk. The moment of inertia of the ball about its center of mass is Icom=2/5MR2.
(a) Find the center of mass velocity v and angular velocity ω of the ball as a function of time after it makes contact with the lane and up to the point when it starts to roll without slipping. Note: directions are important here!
(b) Find the center of mass velocity vf and angular velocity ωf of the ball when it just starts to roll without slipping.
(c) Find the frictional force between the bowling ball and horizontal surface during the ball’s rolling without slipping phase;
(d) Find the center of mass acceleration acom of the ball during its rolling without slipping phase; (e) Find the angular acceleration α of the ball during its rolling without slipping phase;
(f) If the thrower of the ball wants the ball to come to rest before it can reach the point that it will start to roll without slipping, how must the initial conditions, v0 and ω0, be related?
Relevant Equations
Torque net=I(alpha)
Fnet=Ma
v=at+v0
v=r(omega)
I already have a and b, but want to see if anyone is willing to verify my answer for part c. I get 0 for the frictional force between the ground and ball, which would lead d and e to be 0 as well. Physics is rarely that easy so I wanted to make sure I didn’t miss anything.
 

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  • #2
It's not a matter of physics being easy for part (c). It's a matter of reasoning things out. If there were no friction, would the ball start rolling without slipping or would it keep sliding forever?
 
  • #3
kuruman said:
It's not a matter of physics being easy for part (c). It's a matter of reasoning things out. If there were no friction would the ball start rolling without slipping or would it keep sliding forever?

Friction is what causes the ball to start rolling without slipping. If there wasn’t any it would roll forever. But after it starts rolling without slipping, that’s the period I’m concerned about.
 
  • #4
OK, let's look at this from a different angle. Suppose the ball has reached the stage of rolling without slipping. Neglecting dissipative forces, which seems to be the case here, the ball will keep rolling forever at constant velocity.
What does this imply about the force of static friction? I think you know the answer.
Now suppose the ball hits a frictionless patch on the surface. How would the ball's motion change and why?
 
  • #5
kuruman said:
OK, let's look at this from a different angle. Suppose the ball has reached the stage of rolling without slipping. Neglecting dissipative forces, which seems to be the case here, the ball will keep rolling forever at constant velocity.
What does this imply about the force of static friction? I think you know the answer.
Now suppose the ball hits a frictionless patch on the surface. How would the ball's motion change and why?

Velocity would be constant on a frictionless patch. I don’t see how it could change without any forces acting on it.
 
  • #6
Curtiss Oakley said:
Velocity would be constant on a frictionless patch. I don’t see how it could change without any forces acting on it.
That's right, but would the ball still rotate about its center or would it just slide without rotating?
 

FAQ: Bowling Ball Changing Rotational Direction

1. How does changing the rotational direction of a bowling ball affect its trajectory?

Changing the rotational direction of a bowling ball can greatly impact its trajectory. When a bowling ball is released with a clockwise rotation, it will curve to the left, while a counterclockwise rotation will cause it to curve to the right. This is due to the Magnus effect, which is the force that causes a spinning object to curve in the direction of its spin.

2. What factors can influence the rotational direction of a bowling ball?

The rotational direction of a bowling ball can be influenced by several factors, including the release angle, the amount of spin applied, and the condition of the lane. A release angle that is more perpendicular to the lane will result in a straighter trajectory, while a release angle that is more parallel to the lane will cause a greater rotational direction. The amount of spin applied can also affect the rotational direction, with a higher spin resulting in a greater curve. Additionally, the condition of the lane, such as the amount of oil, can impact the rotational direction of a bowling ball.

3. Can a bowler control the rotational direction of a bowling ball?

Yes, a skilled bowler can control the rotational direction of a bowling ball through their release technique and the amount of spin applied. By adjusting the release angle and the amount of spin, a bowler can manipulate the rotational direction to achieve their desired trajectory. This requires practice and skill, as well as an understanding of the mechanics of bowling.

4. How does the weight and surface of a bowling ball affect its rotational direction?

The weight of a bowling ball can impact its rotational direction because a heavier ball will have more momentum and be more resistant to changes in direction. On the other hand, a lighter ball will be easier to manipulate and change its rotational direction. The surface of the ball can also play a role, as a rougher surface will create more friction with the lane and result in a greater rotational direction, while a smoother surface will have less friction and result in a straighter trajectory.

5. Is it possible to change the rotational direction of a bowling ball after it has been released?

No, once a bowling ball has been released, the rotational direction is set and cannot be changed. However, a skilled bowler can anticipate and adjust for the rotational direction by aiming at a different target or using a different release technique for their next throw. Additionally, factors such as lane conditions and oil patterns can also change the rotational direction of a bowling ball between throws.

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