HDE Section 2: Momentum

Question 1

Is momentum a vector?

Answer 1

Momentum is a vector.

Question 2

What is a good way to think of it? (Momentum)

Answer 2

It can be thought of as a measure of how difficult it is to stop something moving

Question 3

It is represented by _ in formulae. (Momentum)

Answer 3

It is represented by p in formulae.

Question 4

Calculate the momentum of a 640 g stone thrown with a velocity of 25 ms-1.

Answer 4

0.64kg x 25ms^-1 = 16

Question 5

Write down the unit of momentum?

Answer 5

Ns

Question 6

Scalar or vector?

Distance
Mass
Velocity
Energy
Weight
Acceleration
Temperature
Momentum
Displacement
Force
Speed

Answer 6

S
S
V
S
V
V
S
V
V
S
S

Question 7

Are collisions in linear momentum always conserved?

Answer 7

In collisions linear momentum is always conserved (provided no external force acts on the bodies).

Question 8

A 0.1kg bullet is fired from a gun at 20m/s. The bullet lands in a 1.5kg wood block. What is the velocity of the bullet and wood block?

Answer 8

1.25

Question 9

0.2kg bullet is fired from a gun at 10m/s. The bullet lands in a 1.2kg wood block. What is the velocity of the bullet and wood block?

Answer 9

1.4

Question 10

A 120g bullet is fired from a gun at 25m/s. The bullet lands in a 1.0kg wood block. What is the velocity of the bullet and wood block?

Answer 10

2.7

Question 11

A trolley of mass 400 g moving at 2 ms-1 collides and sticks to a stationary trolley of mass 800 g. Calculate the velocity of the trolleys after the collisions.

Answer 11

0.67

Question 12

An airgun pellet of mass 0.60 g is fired into a wooden block of mass 119.4 g resting on a smooth surface. If the initial velocity of the block and pellet after the impact is 0.30 ms-1 calculate the speed of the pellet before the collision.

Answer 12

60

Question 13

What is an impulse?

Answer 13

Where the change in momentum is equal to the resultant force multiplied by time, this is known as the impulse.

Question 14

When two objects move apart in opposite directions the force on each must be the same (2nd law) and the time must also be the same, so the impulse on each object ____________

Answer 14

When two objects move apart in opposite directions the force on each must be the same (2nd law) and the time must also be the same, so the impulse on each object is the same.

Question 15

State the unit of Impulse.

Answer 15

Ns

Question 16

Calculate the impulse needed to Increase the velocity of a body of mass 2.5kg from 3.2ms, to 4.8 ms’.

Answer 16

4

Question 17

Calculate the average resultant force needed to Increase the momentum of a cyclist from 400Ns to 600Ns In a time of 20s.

Answer 17

10

Question 18

A falling ball of mass 400g hits the ground travelling at 6.0ms. and bounces up at 4.0 ms-f. Calculate the change in momentum of the ball during the impact.

Answer 18

4

Question 19

A cannon of mass 1200 kg fires a cannonball of mass 5.0 kg in a horizontal plane. If the recoil velocity of the cannon is 0.25ms., calculate the velocity of the cannonball as it Leaves the barrel.

Answer 19

60