A juggler throws a bowling pin straight up in the air....

[Anama Skout]

Homework Statement

A juggler throws a bowling pin straight up in the air. After the pin leaves his hand and while it is in the air,
which statement is true? (a) The velocity of the pin is always in the same direction as its acceleration. (b) The velocity of the pin is never in the same direction as its acceleration. (c) The acceleration of the pin is zero.
(d) The velocity of the pin is opposite its acceleration on the way up. (e) The velocity of the pin is in the same direction as its acceleration on the way up.

Homework Equations

None.

The Attempt at a Solution

I stated that all choices were wrong, however the solution manual says that (d) is right. However I think there's an error going on here, since the velocity of an object can never be the same as its acceleration (Why? Dimensional analysis!) I think what they mean is that the direction of the velocity of the pin is opposite its acceleration on the way up. Am I right on that?

 

[jbriggs444]

[...](d) The velocity of the pin is opposite its acceleration on the way up. (e) The velocity of the pin is in the same direction as its acceleration on the way up.

I think what they mean is that the direction of the velocity of the pin is opposite its acceleration on the way up. Am I right on that?

I agree that the intended meaning of d is that the direction of the acceleration and of the velocity are opposite.

 

[DaniV]

The answer is d because this answer say that velocity and accelration opposite only when the pin moving up, the description of the movment of the pin after the hand leaves it, in some starting velocity opposite direction realvity to Earth ,
while gravity acceleration is making the velocity decreased while it in the air,
After some time the velocity would be zero and the pin reach the maximum point above ground, after this the velocity would be in the same direction as the acceleration toward Earth the velocity will increase till the pin hit the ground.

 

[Anama Skout]

The answer is d because this answer say that velocity and accelration opposite only when the pin moving up, the description of the movment of the pin after the hand leaves it, in some starting velocity opposite direction realvity to Earth ,
while gravity acceleration is making the velocity decreased while it in the air,
After some time the velocity would be zero and the pin reach the maximum point above earth, after this the velocity would be in the same direction as the acceleration toward Earth the velocity will increase till the pin hit the ground.

Did you read what I stated? I agreed that if they meant that "the direction of the velocity of the pin is opposite its acceleration on the way up." then (d) is surely right.

 

[insightful]

I agreed that if they meant that "the direction of the velocity of the pin is opposite its acceleration on the way up." then (d) is surely right.

This is a good lesson in making judgement calls.