Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

If we apply the brakes to a moving car, it comes to rest. This shows that force can make a moving object go slower.

  1. True

  2. False

  3. Ambiguous

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

Answer is A.

Friction prevents objects from moving or slows them down. It also causes wear on surfaces as they rub against each other and generates heat. Thus energy is wasted in overcoming friction. Hence, the force of friction can slow down an object.
Hence, the statement is true.

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

Eqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force ?

  1. Eqbal

  2. Seema

  3. Both apply same force

  4. cant say
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Force of friction arises because of interlocking of irregularities on the two surfaces in contact. When a heavy object is placed on the floor, the interlocking of irregularities on the surface of box and floor become strong. This is because the two surfaces in contact are pressed harder. Hence, more force is required to overcome the interlocking. Thus to push the heavier box, Seema has to apply a greater force than Eqbal.

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

State whether true or false.
If a body is moving with a constant speed along a straight line, then in order to change its direction of motion, an external force or its component has to act in a direction normal to the direction of motion.

  1. True

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

Here, body is moving with constant velocity. 

To change its direction of motion,  an external force must act in the direction opposite to the velocity, so given statement is false. 

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

In which of the following cases, the net force acting on the body is not zero?

  1. An object floating in mercury

  2. A ball freely falling from a certain height

  3. A cork floating on the surface of water.

  4. All of the above cases.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the case of falling freely under gravity.

  By newton second law
 $F _{net}=ma$
in this case $a=(-g)$
Hence there is net force in downward direction.
Rest are all balanced.

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

Two bodies of masses ${m} _{1}$ and ${m} _{2}$ are acted upon by a constant force $F$ for a time $t$. They start from rest and acquire kinetic energies ${E} _{1}$ and ${E} _{2}$ respectively. Then $\dfrac{{E} _{1}}{{E} _{2}}$ is

  1. $\dfrac{{m} _{1}}{{m} _{2}}$
  2. $\dfrac{{m} _{2}}{{m} _{1}}$
  3. $1$
  4. $\dfrac{\sqrt{{m} _{1}{m} _{2}}}{{m} _{1}+{m} _{2}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bodies of mass $m _1$ and $m _2$ acted on by force F (say) for time t. Acceleration in mass $m _1$= $\dfrac{F}{m _1}$
Acceleration in mass $m _2$= $\dfrac{F}{m _2}$
Velocity acquired during this time for mass $m _1$
$v _1=\dfrac{F}{m _1} t$
Velocity acquired during this time for mass $m _2$
$v _2=\dfrac{F}{m _2} t$

Ratio of kinetic energy acquired
$\dfrac{E _1}{E _2}=\dfrac{\dfrac{1}{2}m _1v _1^2}{\dfrac{1}{2}m _2v _2^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _1\times (\dfrac{F}{m _1} t)^2}{m _2\times (\dfrac{F}{m _2} t)^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _2}{m _1}$

Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

If $f(x) = \dfrac {1}{\sqrt {2\pi}} e^{-\dfrac {x^{2}}{2}}$, then for which of the following values of $x$ does $f(x) = 0.33$?

  1. $0.62$
  2. $0.71$
  3. $1.36$
  4. $3.93$
  5. $4.95$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The function is the standard normal distribution density. Solving 1/sqrt(2*pi) * exp(-x^2 / 2) = 0.33 requires evaluating the normal distribution table or a calculator. For x=0.62, f(0.62) is approximately 0.33.

Multiple choice physics force and types of force concept of force and its unit force - push or pull forces

In which direction does a car at rest move when pushed by a few persons?

  1. In the direction opposite to push

  2. In the direction of the push

  3. Making an acute angle with the push

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To move a car, their must be interactions between the men and the car. The interaction is exerted in terms of push and the car moves in the direction of push, i.e., in the direction of the force applied.