Newton’s First Law Of Motion - Practice Questions & MCQ

Newton’s 1st law of motion states that if the (vector) sum of all the forces acting on a particle is zero, then and only then does the particle remains unaccelerated, i.e., remains at rest or move with constant velocity.

• - If $\mathrm{F}_{\text {net }}=0 \Rightarrow \mathrm{a}_{\text {net }}=0 \Rightarrow$ forces in all directions are zero, i.e, $\sum \vec{F}_x=0, \sum \vec{F}_y=0, \sum \vec{F}_z=0$

• Newton’s first law is also called the law of inertia.

• Newton’s laws are valid in an inertial frame of reference but are not valid in a non-inertial frame of reference.

                          Frame of reference

• A frame of reference is a system of coordinate systems and clocks.

• Types of frame of reference:

1. Inertial frame of reference- A frame which is at rest or moving with uniform velocity.

                                Example- 1. Car moving with velocity v on a straight road.

                                                 2. Lift at rest.

                          2.  A non-inertial frame of reference- frame which is accelerated and does not have a constant velocity.

                               Example- 1. The frame traveling in a straight line but speeding up or slowing down.

                                               2. The frame traveling along a curved path.