A block of mass m is released from rest at the top of an incline that makes an angle a with the horizontal. The coefficient of kinetic friction between the block and incline is mk. The top of the incline is a vertical distance h above the bottom of the incline. Derive an expression for the work Wf done on the block by friction as it travels from the top of the incline to the bottom. When a is decreased, does the magnitude of Wf increase or decrease?

A block of mass m is released from rest at the top of an incline that makes an angle a with the horizontal. The coefficient of kinetic friction between the block and incline is mk. The top of the incline is a vertical distance h above the bottom of the incline. Derive an expression for the work Wf done on the block by friction as it travels from the top of the incline to the bottom. When a is decreased, does the magnitude of Wf increase or decrease?

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