Tag: first law of motion

The ball is moving with a constant velocity, this implies the sum of external forces is zero

Any curve path can be assumed as summation if small circular arcs  of different radii. For a path to move at circular arc, there must be some force to provide it centripetal force to remain it in circular path. It is not possible to have motion along curved path without any force.

The relative motion between ball and toy wagon is zero before being pulled. As the wagon is pulled, the inertia of ball causes ball to maintain its state of rest, so the ball rolls backwards when wagon is moved in forward direction.

In a moving bus, passengers are in motion along with bus. When brakesare applied to stop a moving bus, bus comes in the position of rest. But because of tendency to be in the motion a person falls in forward direction.Similarly, when a bus is accelerated from rest, the tendency to be in rest, a person in the bus falls backwards.

Whenever an external force acts on a body there is a change in motion of the body. 

Luggage kept on the roof of a bus has the tendency to maintain its state of rest when bus is in rest and to maintain the state of motion when bus is in motion according to Newtons First Law of Motion. When bus will come in motion from its state of rest, in order to maintain the position of rest, luggage kept over its roof may fall down(backward). Similarly, when a moving bus will come in the state of rest or there is any sudden change in velocity because of applying of brake, luggage may fall down(forward) because of its tendency to remain in the state of motion.
This is the cause that it is advised to tie any luggage kept on the roof a bus with a rope so that luggage can be prevented from falling down.

The horse tied to cart is standing stationary on road denotes that the net force acting on the horse as well as the cart individually is zero. If it is standing stationary, it means that horse is applying force on the road perpendicularly and road is also applying same magnitude of force in the opposite direction, which makes the net force on horse to be zero and hence no forward force on the horse is there.

The table exerts a frictional force on the coin in the reverse direction and thus the coin stops across the table.

First Law of Newton states that when viewed in an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity unless acted upon by an external force.

Newton's first law of motion states that if an object experiences no net force, then its velocity is constant. So, force is not required to keep object moving with uniform velocity.