Advertisements
Advertisements
Question
State and explain the law of inertia (or Newton's first law of motion).
Advertisements
Solution
Statement of Newton's first law: If a body is in a state of rest, it will remain in the state of rest, and if the body is in the state of motion, it will remain moving in the same direction with the same speed unless an external force is applied on it.
Explanation: Newton's first law can be explained in the following two parts:
(i) Definition of inertia: The 1st part of Newton's first law of motion gives the definition of inertia, according to which an object cannot change its state by itself.
Example: A book lying on a table will remain in its position unless it is displaced.
(ii) Definition of force: The 2nd part of Newton's first law defines force, according to which force is that external cause which can move a stationary object or which can stop a moving object.
Example: A book lying on a table is displaced from its place when it is pushed.
APPEARS IN
RELATED QUESTIONS
When a carpet is beaten with a stick, dust comes out of it. Explain.
A plumb bob is hung from the ceiling of a train compartment. If the train moves with an acceleration 'a' along a straight horizontal track , the string supporting the bob makes an angle tan−1 (a/g) with the normal to the ceiling. Suppose the train moves on an inclined straight track with uniform velocity. If the angle of incline is tan−1 (a/g), the string again makes the same angle with the normal to the ceiling. Can a person sitting inside the compartment tell by looking at the plumb line whether the train is accelerating on a horizontal straight track or moving on an incline? If yes, how? If not, then suggest a method to do so.
A force F1 acts on a particle accelerating it from rest to a velocity v. Force F1 is then replaced by F2 which decelerates the particle to rest.
A block of mass 2 kg placed on a long frictionless horizontal table is pulled horizontally by a constant force F. It is found to move 10 m in the first seconds. Find the magnitude of F.
When a train starts, the head of a standing passenger seems to be pushed backward. Analyse the situation from the ground frame. Does it really go backward? Coming back to the train frame, how do you explain the backward movement of the head on the basis of Newton's laws?
Derive the relation between newton and dyne.
Classify the types of force based on their application.
In a legend, the hero-kid kicked a toy pig so that it is projected with a speed greater than that of its cry. If the weight of the toy pig is assumed to be 5 kg and the time of contact 0.01 sec., the force with which the hero-kid kicked him was ______.
(Speed of cry = 330 m/s)
How is force defined according to Newton’s First Law?
When does an object accelerate?
