Linear, Angular and Projectile Motion

Question 1

What’s linear motion

Answer 1

A motion in a straight or a curved line with all body parts moving in the same direction at the same speed i.e a javelin moves in a straight line

Question 2

What causes linear motion

Answer 2

Direct force being applied to an objects centre of mass

Question 3

What descriptors are linked to linear motion (10)

Answer 3

• Distance
• Displacement
• Speed
• Velocity
• Acceleration
• Deceleration
• Mass
• Weight
• Inertia
• Momentum

Question 4

What are the two categories of descriptors linked to linear motion

Answer 4

Scalar and Vector

Question 5

What are scalar quantities

Answer 5

Quantities described in terms of size or magnitude

Question 6

Name the scalar quantities linked to linear motion

Answer 6

• Distance
• Speed
• Mass
• Inertia

Question 7

What are vector quantities

Answer 7

Quantities described in terms of size and direction

Question 8

Name the vector quantities linked to linear motion

Answer 8

• Displacement
• Velocity
• Acceleration
• Deceleration
• Weight
• Momentum

Question 9

What are distance and displacement

Answer 9

Measurements that are used to describe a body’s motion

Question 10

What’s distance

Answer 10

• The length of the path a body follows when moving to a point and always has a positive value
• E.g. a 400m runner runs 400m

Question 11

What’s displacement

Answer 11

• The length of a straight line joining the start and finish points and is the shortest distance between two points
• E.g. the displacement of a 400m is 0 because the start/finish is the same and the displacement of a 200m is the number of metres the crow flies across the track from start to finish

Question 12

What’s speed

Answer 12

The rate of change of position

Question 13

What’s the equation for speed

Answer 13

Speed (m/s-1) = Distance covered (m)
——————————-
Time taken (s)

Question 14

What’s velocity

Answer 14

The rate of change of position with reference to direction. This means it’s a more precise description of motion

Question 15

What’s the equation for velocity

Answer 15

Velocity (m/s-1) = Displacement (m)
——————————-
Time taken (s)

Question 16

Define acceleration and deceleration

Answer 16

The rate of change of velocity

Question 17

What’s the equation for acceleration (or deceleration)

Answer 17

Acceleration (m/s2) = Final V - Initial V (m/s)
——————————-
Time taken (s)

Question 18

What’s angular motion

Answer 18

• Movement around a fixed point (eg. a gymnast performing a somersault) that occurs when a force is applied outside the centre of mass
• An off-centre force is referred to as eccentric force (torque)

Question 19

What’s torque

Answer 19

The rotational force of a body that causes an object to turn around its axis of rotation

Question 20

What are the three axes

Answer 20

• Frontal (side to side)
• Sagittal (front to back)
• Vertical (top to bottom)

Question 21

What descriptors are linked to angular motion

Answer 21

• Torque
• Angular velocity
• Inertia
• Angular momentum

Question 22

What’s angular velocity

Answer 22

Refers to the angular displacement that’s covered in a certain time

Question 23

What’s the equation for angular velocity

Answer 23

Angular velocity = Angular displacement (rad)
(Rad/s) ————————————-
Time taken (s)

Question 24

What’s inertia and moment of inertia

Answer 24

The resistance of change of linear motion, moment of inertia is therefore resistance of a body to angular motion, and depends on two factors

Question 25

What two factors does moment of inertia depend on

Answer 25

• Mass of the body/object
• Distribution of mass from the axis of rotation

Question 26

How does mass of the body/object affect moment of inertia

Answer 26

The greater the mass, the greater the resistance to change and therefore the greater the moment of inertia

Question 27

How does distribution of mass from the axis of rotation affect moment of inertia

Answer 27

The closer the mass is to the axis rotation, the easier it is to turn.
- Increasing distribution = increased moi
- Decreasing distribution = decreased moi

Question 28

Provide an example on the effect of distribution of mass from the axis of rotation on moment of inertia

Answer 28

A somersault a straight position has a higher moment of inertia than the tucked somersault. In a straight position the distribution of the gymnasts mass is further away from the axis of rotation

Question 29

What’s the equation for moment of inertia

Answer 29

Moi (kgm2) = mass (kg) X distribution of mass
from the axis (m2)

Question 30

What’s angular momentum

Answer 30

Spin; it involves the object or body in motion around an axis

Question 31

What two things does angular momentum depend on

Answer 31

• Moment of inertia
• Angular velocity
If moi increases, angular velocity decreases and vice versa

Question 32

What’s the equation for angular momentum

Answer 32

Angular momentum = moi X angular velocity
(Kgm2 rad/s) (Kgm2) (rad/s)

Question 33

Outline the conservation of angular momentum

Answer 33

Angular momentum is conserved unless an external torque acts upon it

Question 34

Provide an example of the conservation of angular momentum

Answer 34

The moment of inertia when a break dancer in the Olympics spins on their head can be manipulated by bringing in their arms and legs closer to the axis of rotation, resulting in a smaller moment of inertia and a large angular momentum