Friction Quiz

1. A $8$ kg box is on horizontal ground with $\mu=0.25$. Find the maximum friction force.

• A. $78.4$ N
• B. $19.6$ N
• C. $2.0$ N
• D. $313.6$ N

2. A $5$ kg box on horizontal ground has $\mu=0.4$. A horizontal force of $15$ N is applied. What is the friction force?

• A. $19.6$ N
• B. $4.6$ N
• C. $49$ N
• D. $15$ N

3. A block is in limiting equilibrium on a rough plane inclined at $\alpha$. Which gives $\mu$?

• A. $\mu=\tan\alpha$
• B. $\mu=\sin\alpha$
• C. $\mu=\cos\alpha$
• D. $\mu=\frac{1}{\tan\alpha}$

4. A body slides on a rough surface. Which statement is correct?

• A. $F<\mu R$
• B. $F=\mu R$ in the direction of motion
• C. $F=\mu R$ opposing the motion
• D. $F=0$

5. A $10$ kg block slides on horizontal ground, $\mu=0.3$, at $6\ \text{m s}^{-1}$ with no other horizontal force. How far does it travel before stopping?

• A. $12.2$ m
• B. $1.84$ m
• C. $6.12$ m
• D. $2.04$ m