Exploring Forces MCQs for UPSC Prelims

A brick weighs $30\ \text{N}$ in air. When it is fully immersed in water, a spring balance holding it reads $22\ \text{N}$. The apparent loss in weight of the brick is

1. A $8\ \text{N}$
2. B $22\ \text{N}$
3. C $30\ \text{N}$
4. D $52\ \text{N}$

A box is dragged along a floor by a rope pulling with $60\ \text{N}$ towards the right. Friction opposes the sliding with $22\ \text{N}$. A second rope now also pulls the box with $12\ \text{N}$ towards the left. The net force on the box is

1. A $38\ \text{N}$ towards the right
2. B $26\ \text{N}$ towards the right
3. C $50\ \text{N}$ towards the right
4. D $26\ \text{N}$ towards the left

Assertion (A): Water exerts no upward force on an object that sinks to the bottom. Reason (R): A sinking object still pushes aside some water as it goes down.

1. A Both A and R are true, and R is the correct explanation of A
2. B Both A and R are true, but R is not the correct explanation of A
3. C A is true, but R is false
4. D A is false, but R is true

The same wooden block is dragged first over a smooth glass sheet and then over a sheet of sandpaper of the same size. The friction on the block is

1. A zero on the sandpaper
2. B greater on the glass
3. C greater on the sandpaper
4. D the same on both, since the block is the same

A tin is sealed with nothing but air inside and placed gently on water. It will most likely

1. A float on the surface
2. B sink straight to the bottom
3. C hang in the middle of the water without moving
4. D dissolve in the water

Which of these is the clearest example of a muscular force?

1. A A farmer lifting a sack of grain onto his shoulder
2. B A comb picking up bits of paper after being rubbed on dry hair
3. C An apple falling from a branch
4. D A magnet drawing a pin across a table