ch6

Question 1

work measured by

Answer 1

joule

Question 2

torque measured by

Answer 2

Nm

Question 3

angular displacement measured by

Answer 3

rad

Question 4

power of rotation measured by

Answer 4

watt

Question 5

angular momentum definition

Answer 5

angular momentum of the rigid object around its rotational axis is a linear momentum torque

Question 6

angular momentum measured by

Answer 6

kg.m2/s

Question 7

what does angular momentum depend on

Answer 7

1. The inertia torque (I)

2. The angular velocity(𝛚),

Question 8

What does linear momentum depends on?

Answer 8

its mass (m)
2. its linear velocity (𝒗).

Question 9

What is the statement of the conservation of angular momentum law

Answer 9

When a net external torques influencing in a rigid object is zero, then the total angular momentum of the rigid object remains constant.

Question 10

Give the reason: In the sport of ice skating, the speed of rotation of the skater increases when he brings his legs and arms to his body?

Answer 10

When his arms are joined to his body, it means that the torque inertia around axis decreases

Question 11

If a disc rotated around its axis with a regular angular momentum, the amount of one of
the following quantities is not zero

Answer 11

Angular velocity of the disc

Question 12

A student stands at the edge of a circular platform that rotates horizontally around a
vertical axis passing through its center. If the student approaches the center of the
platform slowly (without the effect of external torque), the student's angular momentum

Answer 12

Remains constant

Question 13

-

Answer 13

-

Question 14

A train rotating on a circular rail in a horizontal level with constant speed then the
thing change in the train wheel is

Answer 14

Angular momentum

Question 15

Balance on a moving bike easier than balance on a parked bicycle.

Answer 15

because it will increase the inertua which will increase the angular momentym

Question 16

2-A body can have an angular momentum even though the angular momentum in it is
zero?

Answer 16

ANS/ Because angular velocity is constant ,so the change in angular momentum equal
zero

Question 17

The person extends his arms (or holds a horizontal stick) when walking on a tight
horizontal rope.

Answer 17

In order increase the torque of inertia

Question 18

Define the Periodic Motioand give example for it.n

Answer 18

The movements repeat themselves over and over again at regular intervals around their positions of stability.
The motion of the pendulum of the wall clock.
2. The movement of strings in the musical instruments.

Question 19

What is the restoring force

Answer 19

The power of the body to restore the position of stability that appear when the body displaced from the position of stability or when it moves away.

Question 20

Define the vibration motion

Answer 20

The movement of the body back and forth (in opposite directions) on both sides of its stabilization position

Question 21

Define the Stabilization position

Answer 21

Stabilization position:- It is the point at which a vibrating body is at rest.

Question 22

Give the reason: the vibration amplitude of vibration movement is gradually damped?

Answer 22

due to forces like friction and air resistance

Question 23

What are the conditions that required to generation and continuity of vibration motion?

Answer 23

Restoring force.

• Continuity.
• Source equipped with energy.

Question 24

What is represent the restoring force of the spring?

Answer 24

the restoring force of the spring is represented by Hooke’s Law as follows: 𝐒𝐩𝐫𝐢𝐧𝐠 𝐟𝐨𝐫𝐜𝐞 (𝐅 )=−(𝐬𝐩𝐫𝐢𝐧𝐠 𝐜𝐨𝐧𝐬𝐭𝐚𝐧𝐭)×𝐝𝐢𝐬𝐩𝐥𝐚𝐜𝐞𝐦𝐞𝐧𝐭 𝐅 𝐫𝐞𝐬=−𝐤×𝐱⃗
Where:

Question 25

simple harmonic motion

Answer 25

a vibrational motion on a straight line, which the restoring force are directly proportional with the displacement

Question 26

Is every vibrating motion a simple harmonic motion?

Answer 26

no unless its path is on a straight line.

Question 27

Is every simple harmonic motion an vibrating motion

Answer 27

yes

Question 28

full wave

Answer 28

is the motion of a vibrating body when it passes the sam epoint twice

Question 29

Wave amplitude

Answer 29

is the maximum displacement of the vibrating body from its position of stability.

Question 30

Frequency:

Answer 30

the number of vibrations that the object vibrates in one second and it is measured by Hertz (Hz).

Question 31

What is the simple pendulum

Answer 31

ball suspended at the end of a weightless and Non-elongated thread of length (L), and the other and is fixed by a fixed point

Question 32

What is the influence causing the acceleration of the ball in the pendulum

Answer 32

restoring force

Question 33

The tension in the thread does not affect the movement

Answer 33

because it is perpendicular to the arc

Question 34

What is the damping simple harmonic motion?

Answer 34

It is the vibrational movement in which the amplitude of the vibration of the body is constantly reduced until it disappears due to the presence of a friction force

Question 35

What is required for a system to vibrate for a certain period of time?

Answer 35

What is required for a system to vibrate for a certain period of time? ANS/ Continuously supplying it with power to compensate for the energy lost during each pulse by doing work against the forces of friction

Question 36

What are the benefits of damping vibration?

Answer 36

Damping vibration also has practical application benefits. In the vehicle’s shock absorber system (suspension), the shock absorbers dampen the vibrations caused by the vehicle’s passing on road bumps notice

Question 37

wave motion. give example for it.

Answer 37

Disruption of the surface of static water when a stone is thrown into it and the energy-carrying waves are in the form of concentric circles from the point that the stone fall in the sides.

• The movement of seismic waves in the earth’s crust energy transporter on the surface of the earth.
• The spread of the sound of the strings of musical instruments vibrating in the air through the vibrations of air molecules.

Question 38

Define the pulse.

Answer 38

the disturbance generated by the very quickly movement of one end of a string top or bottom.

Question 39

Define the pulse amplitude.

Answer 39

It is the maximum displacement of particles from their resting position when the wave moves up or down.

Question 40

speed of the wave in the string? And What does it depends on?

Answer 40

The tension of the string (T).

- The mass of the length unit of the string (linear mass density) 𝛍.