Question

Identical green blocks sit still on two different ramps made of the same material (same surface texture). Ramp $1$ is not as steep as ramp $2$, as can be seen in the diagram below.
Which block experiences a greater force of friction and why?

• A. The block on ramp $1$ experience more frictional force because the normal force block $1$ by the ramp is greater for it than for block $2$
• B. The block on ramp $2$ experience more frictional force because the normal force block $2$ by the ramp is greater for it than for block $1$
• C. The block on ramp $1$ experiences more frictional force because the component of the force of gravity down the ramp is greater on block $1$ than it is on block $2$, and the force of friction must be equal to this component of gravity
• D. The block on ramp $2$ experiences more frictional force because the component of the force of gravity down the ramp is greater on block $2$ than it is on block $1$, and the force of friction must be equal to this component of gravity
• E. The force of friction acting on each block is the same

Answer 1

The correct option is D The block on ramp $2$ experiences more frictional force because the component of the force of gravity down the ramp is greater on block $2$ than it is on block $1$, and the force of friction must be equal to this component of gravity

As the blocks are still therefore frictional force should be equal to the force which is trying to take the blocks down .Now the force which tries to take blocks down will be the component of weight (gravitational force) of the block which is parallel to the slope of ramp , $mg\sin \theta$ ,

we can see from the diagrams that value of $\theta$ for ramp 2 is greater than ramp 1 therefore to balance the frictional force , the value of force $mg\sin \theta$ will be greater on block on ramp 2 than ramp 1. D is the right option .