Pulley

Q.

An effort of 240 N overcome a useful load 1000 N when applied to a block and system of pulleys, such that the weight movable block and friction is 200 N.
Calculate the efficiency of the system (to the nearest integer).

1. 83%

2. 79%

3. 91%

4. 89%

Q. A skydiver jumps from an aircraft. Identify the forces ​P and Q acting on him.​

1. P – Gravitational Force​
   Q – Air Friction​
2. P – Air Friction​
   Q – Gravitational Force​
3. P – Electrostatic Force​
   Q – Gravitational Force​
4. P – Electrostatic Force​
   Q – Magnetic Force​

Q.

The given figure shows a weightless lever in equilibrium. Neglect friction at the fulcrum F.


Calculate the mechanical advantage for the given lever.

1. $\frac{Effortarm}{Loadarm}$

2. $\frac{loadarm}{Effortarm}$

3. $\frac{2\times Effortarm}{Loadarm}$

4. $\frac{Effortarm}{2\times Loadarm}$

Q.

To move in forward direction, the swimmer needs to push water in _______ direction.

1. forward
2. backward
3. sideways

Q. A body of mass $5kg$ moving on a horizontal surface with a velocity of $10m{s}^{-1}$ comes to rest in $2s$. The force required to make this body move with a velocity of $10m{s}^{-1}$ on the same surface is:

1. Zero
2. $10N$
3. $25N$
4. $50N$

Q. A block of base $10cm\times 10cm$ and height $15cm$ is kept on an inclined plane. The coefficient of friction between them is $\sqrt{3}$ The inclination $\theta$ of this inclined plane from the horizontal plane is gradually increased from $0^o$.Then :

1. at $\theta ={30}^o$, the block will start sliding down the plane.
2. the block will remain at rest on the plane up to certain $\theta$ and then it will topple.
3. at $\theta ={60}^o$, the block will start sliding down the plane and continue to do so at higher angles.
4. at $\theta ={60}^o$, the block will start sliding down the plane and on further increasing $\theta$, it will topple at certain $\theta$.

Q. A block is stationary on a rough inclined plane. How many forces are acting on the block

Q. Why is acceleration a vector quantity ?