- #1

Amit86

- 8

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Hi all,

I'm working on a problem from the Feynman exercise book, and have been racking my brains for an answer, so would really appreciate some help here. The problem seems simple enough:

A ball with a 3cm radius, weighing 1kg rests on an inclined plane (angle alpha) and also touches a vertical wall. Neglect friction.

(see attached diagram)

What is the force of the ball acting on the wall (Fw)?

The answers in the back gives

Fw= tan(alpha) kg.wt

I got the force due to gravity acting down the plane, Fr = 9.81.sin(alpha). The horizontal component of this force, which to my mind is the force acting on the wall, is

Fr

What am I missing here?!

Thanks!

Amit

I'm working on a problem from the Feynman exercise book, and have been racking my brains for an answer, so would really appreciate some help here. The problem seems simple enough:

A ball with a 3cm radius, weighing 1kg rests on an inclined plane (angle alpha) and also touches a vertical wall. Neglect friction.

(see attached diagram)

What is the force of the ball acting on the wall (Fw)?

The answers in the back gives

Fw= tan(alpha) kg.wt

I got the force due to gravity acting down the plane, Fr = 9.81.sin(alpha). The horizontal component of this force, which to my mind is the force acting on the wall, is

Fr

_{hor}=9.81* sin(alpha)cos(alpha)What am I missing here?!

Thanks!

Amit