Physics Practice: Machines (Mock Test 3 - Advanced)
1. A crowbar of length $150 \text{ cm}$ has its fulcrum at a distance of $25 \text{ cm}$ from the load. If an effort of $50 \text{ kgf}$ is applied, the load that can be lifted is:
2. Why does the Mechanical Advantage (M.A.) of a block and tackle system decrease when the weight of the lower block increases?
3. A single movable pulley is used in combination with a single fixed pulley. The Velocity Ratio of this system is:
4. For a Class II lever, the Mechanical Advantage (M.A.) is always greater than $1$ because:
5. A block and tackle system has $4$ pulleys. If the efficiency is $75\%$, what load can be lifted by an effort of $200 \text{ kgf}$?
6. Which of the following describes the "Law of Lever"?
7. A woman uses a sugar tongs to lift a cube of sugar. Her fingers apply the effort in the middle. This is a Class III lever because:
8. The relation between $MA$, $n$ (total pulleys) and $w$ (weight of lower block) is given by $MA = n - (w/E)$. This implies:
9. In a block and tackle system with $n$ pulleys, if the effort is applied in the downward direction, the number of strands of string supporting the load is:
10. To open a soda bottle with an opener, the opener acts as a Class II lever. Why?
11. A machine with $VR = 5$ is used to lift a $500 \text{ N}$ load. If the work input is $1250 \text{ J}$ for a displacement of $2 \text{ m}$ of the load, the efficiency is:
12. In which class of lever can the Mechanical Advantage be $1$, $>1$ or $<1$?
13. The gain in torque in a machine comes at the cost of:
14. A system of two pulleys, one fixed and one movable, has a VR of 2. If the effort is $100 \text{ N}$ and load is $150 \text{ N}$, the friction in the pulleys is equivalent to:
15. A knife used to cut fruit acts as a speed multiplier. This is characteristic of:
16. The Velocity Ratio of a machine is a ________ property, while Mechanical Advantage is a ________ property.
17. A lemon squeezer is a Class II lever. If the distance from the hinge to the lemon is $4 \text{ cm}$ and to the handle is $20 \text{ cm}$, the ideal $MA$ is:
18. The string used in a pulley system is assumed to be inextensible and massless to ensure:
19. If $Load = 40 \text{ N}$ and $Effort = 10 \text{ N}$ in an ideal movable pulley, the ratio of distances $d_E : d_L$ must be:
20. The Mechanical Advantage of a machine can be increased by:
