Tag: force and newton's laws of motion

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Questions Related to force and newton's laws of motion

Multiple choice physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

Two bodies $A$ and $B$ having mass $M$ and $m$ respectively possesses same kinetic energy. Given that $M> m$. If ${\rho} _{A}$ and ${\rho} _{B}$ be their momentum, then which of the following statements is true?

  1. ${ \rho } _{ A }={ \rho } _{ B }$

  2. ${ \rho } _{ A }> { \rho } _{ B }$

  3. ${ \rho } _{ A }< { \rho } _{ B }$

  4. It cannot be predicted
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Two bodies A and B having mass m and M respectively possesses same Kinetic energy : 
$K _A = K _B$
In general kinetic energy, $K = \dfrac{1}{2} mv^2 = \dfrac{p^2}{2m}$ where $p$ is momentum. 
$\therefore \dfrac{\rho _A ^2}{2M} = \dfrac{\rho _B ^2}{2m}$
$ \dfrac{\rho _A ^2}{M} = \dfrac{\rho _B ^2}{m}$
But $M>m$ and therefore for above equation to be true $\rho _A ^2 < \rho _B ^2$ or $\rho _A < \rho _B $ 
Multiple choice physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

For constant non zero mass, momentum versus velocity graph is a:

  1. straight line parallel to x- axis

  2. straight line parallel to y- axis

  3. straight line passing through origin

  4. straight line passing through y- axis with an intercept
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

We know that,
Momentum = mass $ \times $ velocity
So, we know that when a graph is plotted, momentum against velocity, it is a straight line passing through the origin because momentum varies linearly with respect to velocity.

Multiple choice physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

A body of mass $2 kg$ is sliding with a constant velocity of $4 m/s$ on a frictionless horizontal table. The net force required to keep the body moving with the same velocity is

  1. $8 N$

  2. $0 N$

  3. $4 N$

  4. $\dfrac { 1 }{ 2 } &nbsp;N$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to newton's first law of motion, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external net force.
Therefore The force required to keep the body moving with the same velocity is zero.