Impulse

Q. Derive the expression of velocity of an object thrown as a projectile at any point of its trajectory

Q. How can we say that the rate of change of momentum is directly proportional to the applied force?

Q.

A cricket player lowers his hands while catching a fast moving ball. Explain why?

Q.

While catching a ball , the cricketer withdraws his hands. Does this reduce the change of momentum of the ball? How is it advantageous?

Q.

The troops equipped to be dropped by parachutes from an aircraft are called paratroopers. Why do paratroopers roll on landing?

Q.

Explain why a feilder on a cricket field covers his hand while catching a cricket ball.

Q. Question 16
Two friends on roller-skates are standing 5 m apart facing each other. One of them throws a ball of 2 kg towards the other, who catches it, How will this activity affect the position of the two? Explain your answer.

Q. Which of the following velocity-mass graph is correct when linear momentum is constant?

जब रेखीय संवेग नियत है, तब निम्नलिखित में से कौनसा वेग-द्रव्यमान आरेख सही है?

1. 
2. 
3. 
4. 

Q.

The physical quantity that remains zero for an object moving with a uniform velocity is (in ideal case):

1. momentum

2. Velocity

3. Mass

4. External force

Q. Why does cricketer move his hand backwards while catching a fast moving cricket ball?

Q. While catching a fast moving cricket ball a fielder in the ground gradually pulls his hand backward with the ball. Explain.

Q.

A fielder pulls his hands gradually with the moving ball while holding a catch. Why does he do this?

1. It reduces the impact of catching the fast moving ball.

2. It reduces the frictional forces between hand and the ball

3. It increases the momentum of the ball.

4. none

Q. A ball weighing 10$gm$ hits a hard surface vertically with a speed of 5$m/s$ and rebounds with the same speed. The ball remains in contact with the surface for 0.01 sec. The average force exerted by the surface on the ball is:

1. 20$N$
2. 10$N$
3. 200$N$
4. 400$N$

Q. A woman dancing in high-heeled shoes accidentally steps on her partner's foot with the heel of her shoe. Even though her partner outweighs her by 400N and can easily lift her off the floor, he feels pain because:

1. her small foot has a large momentum
2. her weight is concentrated into a small area
3. her foot has a large inertia
4. his foot has no inertia

Q.

Due to an impulse, the change in momentum of a body is $1.8kgm{s}^{-1}$. How much is the force acted on it if the duration of the force acting is $0.2s$ ?

1. $9N$

2. $3.6N$

3. $0.36N$

4. $6N$

Q.

_______________ is equal to change in momentum.

Q.

I need some videos regarding the topics of trajectory with formulae

Q. A ball of mass $1kg$ is attached to an inextensible string. The ball is released from the position shown in figure. Find the impulse imparted by the string to the ball immediately after the string becomes taut (Take g=$10m/s^2)$

Q. Find out the reason why an airbag reduces injury to a passenger during a car crash.

1. The air bag reduces the force by reducing the passengers change in velocity.
2. The air bag reduces the change in momentum by increasing the passengers impulse.
3. The air bag reduces the change in velocity by reducing the time it takes the passenger to stop moving.
4. The air bag reduces the force by increasing the time it takes the passenger to stop moving.
5. The air bag reduces the impulse by reducing the change in the passengers momentum.

Q. Which of the following is not a way of reducing the impulsive force?

1. Jumping off a table, a boy bends his knees when he reaches the ground.
2. Polystyrene or cardboard is used when packing fragile items.
3. Cars are designed in the shape of an aerofoil as a safety feature.
4. Thick piece of mattress is used in the high jump event.

Q. Suppose a ball of mass m is thrown vertically upwar with an initial speed v, its speed decreases continuously till it becomes zero . Thereafter , the ball begins to fall downwardand attains the speed v again before striking the ground . It implies that the magnitude of initial and final momentums of the ball are same . Yet , it is not an example of conservation of momentum . Explain why ?

Q. The position (x) - time (t) graph for a particle of mass $1kg$ moving along x-axis is shown in figure. Find impulse on particle at $t=4s$.

Q.

What would be the relation between magnitude of velocity of the gun and bullet after firing, if the mass of gun is less than the mass of bullet? Assume no external force is acting on the gun bullet system.

1. Recoil velocity of gun is higher than the velocity of bullet.

2. Velocity of bullet is higher than the recoil velocity of gun.

3. Recoil velocity of gun is equal to the velocity of bullet.

4. Velocity of bullet is twice than that of recoil velocity of gun.

Q.

a constant force of 12N acts on a body for 4s . find the change in the linear momentum of the body.

Q. A ball of mass $200$ g is projected with a velocity of 30$m/s$ at ${30}^{\circ }$ from horizontal. Using the concept of impulse, find change in velocity in $2$ s. Take $g=10m/s^2$

Q. A particle of mass m strikes elastically on a wall with velocity v at an angle 60? from the wall then magnitude of change in momentum of ball along the wall is ?

Q. A ball is dropped on to a floor .If the coefficient of restitution is 0.5 then loss of energy of the ball on rebounding from the floor is

1. 12.5 %
2. 25 %
3. 50 %
4. 75 %

Q. A fielder pulls his hands back gradually with the moving ball while holding a catch. Why does he do this?

1. It increases the momentum of the ball.
2. It reduces the impact of catching the fast moving ball.
3. It reduces the frictional force between hand and the ball.
4. It increases the speed of ball suddenly.

Q. Q: A Body of mass 60 kg is dragged with just enough force to start moving on a rough surface with coefficients of static and kinetic frictions 0.5 and 0.4 respectively . On applying the same force , what is the acceleration ?(g = 9.8m/s²)

Q. Guess and write, what happen if cricket fielder not pulled back his hand.