Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

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

A batsman hits back a ball straight in the direction of the bowler without changing its initial speed of $12 ms^{-1}$. If the mass of the ball is $0.15\ kg$, determine the change in momentum of the ball. (Assume linear motion of the ball)

  1. $3.6 kg m/s$

  2. $5 kg m/s$

  3. $3.5 kg m/s$

  4. $7 kg m/s$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The initial momentum of ball $P _1 = m\vec{v} $, after batsman hits ball and reverses its direction, momentum of ball $P _2= -m\vec{v} $
Magnitude of change in momentum $\Delta p = \left | P _2-P _1\right | =\left | - 2m \vec{v}\right | =2m \left | \vec{v}\right | $ 
from data given in question $  m=0.15 kg ;\;  \left | \vec{ v} \right |= 12m/ s$
$\Delta P=2\times 0.15\times 12= 3. 6 kg m/ s $

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

A loaded transport truck with a mass of 38000 kg is travelling at 1.20 m/s. What will be the velocity of a 1400 kg car if it has the same momentum?

  1. 32.57 m/s

  2. 30 m/s

  3. 15 m/s

  4. 32.67 m/s
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Momentum of truck $ P _{truck}= m _{truck}v _{truck}$
from given data in question $ m _{truck} = 38000 \; kg;\; v _{truck}= 1.2\; m/s$
$P _{truck}= 38000\times 1.2= 45600 \; kg m/ s$
the momentum of car is equal to momentum of truck $P _{car}= m _{car}v _{car}\Rightarrow v _{car}= 45600/ 1400= 32.57 m/s$

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

An example of a force applied in the direction of motion is:

  1. Opening a door

  2. Applying brakes suddenly to a moving car

  3. A batsman hitting a cricket ball

  4. Drawing water from a well
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

While opening the door the force applied is tangential to the motion of the door.
While applying brakes the motion is on a different axis to the force applied,
When a batsman hits a ball, both the ball and the force applied are in the same direction
While drawing water from the well the motion and the force are in different directions (mostly tangential)

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

A force of $10 N$ acts on a body of mass $20 kg$ for $10 s$ .Change in its momentum is:

  1. $5 kg m/s$

  2. $100 kg m/s$

  3. $200 kg m/s$

  4. $1000 kg m/s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\Delta P = F\Delta t = 10 \times 10 = 100 kg m/s$

Where,
     $\Delta$ P = Change in momentum,
          F = Applied force
     $\Delta$ t  = time for which force has been applied on the body
                   
                          

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

The quantity that best represents the motion of a rigid body is

  1. its mass.

  2. its speed.

  3. its velocity.

  4. its linear momentum.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass of a body is the quantity of inertia possessed by it, or in simpler words, it is the measure of resistance that a body can provide to change in its motion.
Speed is the measure of how fast a body is moving.
Velocity is the measure of how fast a body is moving along with its direction.
Linear momentum is the quantity which denoted the motion of body along with its direction.

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

In which of the following cases the net force is not zero?

  1. A kite skillfully held stationary in the sky

  2. A ball freely falling from a height

  3. An aeroplane rising upwards at an angle of $45^{\circ}$ with the horizontal with a constant speed

  4. A cork floating on the surface of water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If a ball freely falling from a height the net force applied on the ball is not zero as gravity is acting on it.

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

A ball of mass 'm' moves normal to a wall with a velocity 'u' and rebounds with the same speed. The change in momentum of the ball during the rebounding is

  1. 2mu towards the wall

  2. 2mu away from the wall

  3. zero

  4. mu away from the wall
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If the collision of the ball and the wall is elastic one then the change in the momentum of the ball after collision is $= mu-(-mu)=2mu$ away from the wall.

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

The velocity of a body of mass 20 kg increases to 400 kgm/s in 5s. If initial velocity was 10 m/s, what is the momentum before the force acts?

  1. ${200 kg. m/s ^2}$

  2. $300\  kg.m/s$

  3. $200 \ kg.m/ s$

  4. $100 \ kg. m/s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given :   $m =20$ kg        

Initial velocity of the body        $u  = 10$ m/s
Thus initial momentum of the body         $P _i = mu  =20\times 10 = 200$  kg.m/s