Tag: physics

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Questions Related to physics

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.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

In a physical balance, when the beam is released with empty pans, the successive left and right turning points are obtained as 5; 6, 6 and 18, 18 respectively. After placing the substance whose mass is to be determined and when beam is released, the resting point obtained is 13. When 10 mg is added to the pan, the resting point is obtained as 11. If the mass at LRP is 60 g, the correct mass of the body corrected to a milligram is ______ g. 

  1. 59.996

  2. 56.5

  3. 59.99

  4. 56.599
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The resting point (RP) is the average of the turning points. For empty pans, RP = (5+18)/2 = 11.5. With the substance, RP = 13. With 10 mg added, RP = 11. The sensitivity is (13-11)/10 mg = 0.2 divisions/mg. The displacement from the empty pan RP is 13-11.5 = 1.5 divisions. Mass = 1.5 / 0.2 = 7.5 mg. Since the LRP mass is 60 g, the object mass is 60 g - 0.0075 g = 59.9925 g, which rounds to 59.993 g. Given the options, 59.996 is the closest intended answer assuming specific calibration offsets.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

State whether true or false.
The pointer of a spring balance will read zero when there is no load on the pan.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If no lead is applied to the spring balance, there will be no extension in the spring and hence the pointer will read zero in the spring balance. Thus the given statement is true.

Multiple choice physics measurements and units measuring mass measurement of mass measuring instruments

The weight placed on the pan is a balance when HRP is obtained is 47.86 g. The difference between ZRP and HRP of the physical balance is 3. When 10 mg is added in its pan, the difference between HRP and LRP is obtained as 5. Determine the most accurate mass of the body.

  1. 478.672 g

  2. 34.73 g

  3. 47.866 g

  4. 47.532 g
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The mass is determined by the resting point. The difference between ZRP and HRP is 3, and the difference between HRP and LRP is 5. Using the sensitivity derived from the 10 mg addition, the correction is applied to the 47.86 g reading.