Law of Motion MCQ question and answer with solution | Physics Gk MCQs

Imagine you're standing on a perfectly smooth, icy surface – that's what a frictionless surface is like. Friction is what helps your feet grip the ground when you walk or run. Without friction, your feet would just slide. Let's analyze each option: Option A: Sneezing
Sneezing involves internal forces within your body. These forces won't move you on a frictionless surface because there's no external force to push against. This option is incorrect.

Option B: Jumping
When you jump, you push down on the ground (action). The ground pushes back up on you (reaction), and this reaction force propels you upward even without friction. This is due to Newton's Third Law of Motion. On a frictionless surface, jumping causes you to move upward, but due to the lack of friction, you also move horizontally a little bit. This option is correct.

Option C: Running
Running relies on friction between your feet and the ground to propel you forward. Without friction, your feet would just slip. This option is incorrect.

Option D: Rolling
Similar to running, rolling needs friction to work. You wouldn't roll effectively on a frictionless surface. This option is incorrect.

Conclusion:
The only way to move on a frictionless surface is by using an action that creates an equal and opposite reaction, as described in Newton's Third Law. Jumping is the only option that does this. Therefore, the correct answer is Option B: Jumping.

The correct answer is (C) class-III lever.
First, what is a lever? A lever is a simple machine that amplifies an applied force.
There are three classes of levers, distinguished by the relative positions of the fulcrum (pivot point), the load (resistance), and the effort (force applied).

* Class-I Lever: The fulcrum is between the load and the effort. Think of a seesaw.
* Class-II Lever: The load is between the fulcrum and the effort. Think of a wheelbarrow.
* Class-III Lever: The effort is between the fulcrum and the load. Think of your arm when lifting something or tongs.

Now, think about a ladder being used.
The fulcrum is the bottom of the ladder resting on the ground.
The load is at the top of the ladder where someone is working (or where it rests against a wall).
The effort is where you are applying the force to climb the ladder, which is between the bottom (fulcrum) and the top (load).

Since the effort is between the fulcrum and the load, a ladder acts as a class-III lever.
An inclined plane(Option D) is also a simple machine, but a ladder's primary function involves lever action when climbing.