Laws of Motion Flashcards for NEET — 20 cards

First 8 of 20 Laws of Motion flashcards

Read the question, answer it in your head, then open the answer to check yourself.

1. Card 1 of 20

   State Newton's First Law of Motion (Law of Inertia).

   Hint: Inertia is directly proportional to mass.

   Show answerHide answer

   Answer

   A body continues in its state of rest or of uniform motion in a straight line unless compelled by a net external force to change that state.

2. Card 2 of 20

   Define Linear Momentum ($p$) and state its formula.

   Hint: SI Unit: $kg \cdot m/s$

   Show answerHide answer

   Answer

   Momentum is the quantity of motion possessed by a body. Formula: $p = mv$. It is a vector quantity acting in the direction of velocity.

3. Card 3 of 20

   State Newton's Second Law of Motion mathematically.

   Hint: This is the real law of motion from which the 1st and 3rd laws can be derived.

   Show answerHide answer

   Answer

   The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction of the force. $F = \frac{dp}{dt}$. If mass is constant, $F = ma$.

4. Card 4 of 20

   Define Impulse ($J$) and its relation to momentum (Impulse-Momentum Theorem).

   Hint: The area under a Force-Time graph gives Impulse.

   Show answerHide answer

   Answer

   $J = \Delta p = \int F \cdot dt$ Area under F-t graph = Impulse.

5. Card 5 of 20

   State Newton's Third Law of Motion.

   Hint: Action and reaction forces ALWAYS act on TWO DIFFERENT bodies. They never cancel each other out on the same body.

   Show answerHide answer

   Answer

   To every action, there is always an equal and opposite reaction. $F_{AB} = -F_{BA}$.

6. Card 6 of 20

   What is the Law of Conservation of Linear Momentum?

   Hint: Used in collisions, bomb explosions, and rocket propulsion.

   Show answerHide answer

   Answer

   If the net external force on a system is zero, the total linear momentum of the system remains constant. $P_{initial} = P_{final}$.

7. Card 7 of 20

   Write the formula for the recoil velocity ($V$) of a gun of mass $M$ firing a bullet of mass $m$ with velocity $v$.

   Hint: The negative sign indicates that the gun moves in the opposite direction to the bullet. Derived from $MV + mv = 0$.

   Show answerHide answer

   Answer

   $V = - \frac{m \cdot v}{M}$

8. Card 8 of 20

   What is the apparent weight (Normal reaction $N$) of a person of mass $m$ in an elevator accelerating UPWARDS with acceleration $a$?

   Hint: If the elevator moves up with constant velocity, $a = 0$, and $N = mg$.

   Show answerHide answer

   Answer

   $N = m(g + a)$ The apparent weight is greater than the true weight.