4.3 Equations of Motion

Question 1

What is distance?

Answer 1

the total length between two points

Question 2

What is speed?

Answer 2

the total distance travelled per unit of time

Question 3

What is displacement?

Answer 3

the distance of an object from a fixed point in a specified direction

Question 4

What is velocity

Answer 4

the rate of change of displacement of an object

Question 5

What is acceleration

Answer 5

the rate o change of velocity of an object

Question 6

What is the equation of velocity?

Answer 6

v = change in displacement/time

Question 7

what is the equation of acceleration

Answer 7

a = change in velocity/time

Question 8

What is instantaneous speed (or velocity)?

Answer 8

the speed of an object at any given point in time

Question 9

How is acceleration shown on a displacement time graph?

Answer 9

a curved line
- it has a changing velocity

Question 10

How is velocity shown on a displacement time graph?

Answer 10

gradient of a straight line
- may be at a tangent to the curve

Question 11

What is the average speed?

Answer 11

the total distance/ time

Question 12

How do you find average speed on a displacement time graph?

Answer 12

• divide the total displacement by the total time
  gradient of the line

Question 13

what are the 3 motion graphs?

Answer 13

displacement time graphs
velocity time graphs
acceleration time grahs

Question 14

How can you find velocitythe on a displacement time graph?

Answer 14

the gradient
- positive slope represents motion in the positive direction
- negative slope represents motion in the positive direction

Question 15

How do you find the acceleration on a dt graph?

Answer 15

curved line

Question 16

What is the area under the curve of a dt graph?

Answer 16

nothing

Question 17

What does a horizontal line represent on a dt graph?

Answer 17

a state of rest

Question 18

What is the initial displacement of a dt graph?

Answer 18

the y intercept

Question 19

How is the acceleration shown on a velocity time graph?

Answer 19

• the gradient of the slope
• a positive slope represents an increase in velocity in the positive direction
• a negative slope represents an increase in velocity in the negative direction
• a curved line represents non-uniform acceleration

Question 20

How is constant velocity represented on a vt graph?

Answer 20

a horizontal line

Question 21

How is displacement represented on a vt graph?

Answer 21

the area under the curve

Question 22

What can be shown on an acceleration time graph?

Answer 22

• y intercept is initial acceleration
• horizontal line is constant acceleration
• area under the curve is the change in velocity

Question 23

What is the acceleration due to gravity of a bouncing ball?

Answer 23

• always in the same direction in a uniform gravitational field such as earths surface

Question 24

What is the velocity of a bouncing ball?

Answer 24

• because the ball is going up and down it changes direction
• thus the velocity of the ball will change from - to + dependent on the direction

Question 25

In projectiles; what is the time of flight?

Answer 25

how long the projectile is In the air

Question 26

in projectiles; what is the maximum height attained

Answer 26

the height w
at which the projectile is momentarily at rest

Question 27

In projectiles; what is range?

Answer 27

the horizontal distance travelled by the projectile

Question 28

What are the 3 possible scenarios for projectile motion

Answer 28

• vertical projection
• horizontal projection
• projection at an angel

Question 29

What are drag forces

Answer 29

forces that oppose the motion of an object moving through a fluid

Question 30

What are the properties of drag forces?

Answer 30

• always in the opposite direction to the direction of motion of the object
• never speed up an object or start them moving
• slow down an object or keeps them moving air a constant speed
• converts kinetic energy into heat and sound

Question 31

What is lift?

Answer 31

an upwards force on an object moving through a fluid perpendicular to the flow

Question 32

What is the relationship between drag forces and the speed of an object

Answer 32

as the speed increases the drag increases

Question 33

What is air resistance?

Answer 33

an example of a drag force that objects experience when moving through the air

Question 34

what is the relationship with air resistance and th speed of an object?

Answer 34

air resistance increase with the speed of the object

Question 35

What factors effect the maximum speed of the object, other than air resistance?

Answer 35

• cross sectional area
• shape
• altitude
• temprature
• humidity

Question 36

how does air resistance effect projectiles?

Answer 36

• it decreases the horizontal component of the velocity of a projectile
• thus the range and max height is decreased compared to no air resistance

Question 37

what does it mean if air resistance is negligible?

Answer 37

• the air resistance is so small it does not make a difference to the motion of the object.
• thus you do not take any drag forces into account during calculations

Question 38

What is terminal velocity?

Answer 38

the maximum velocity that the object can have
- when drag forces are equal to the gravitational pull on the body and the body will no longer accelerate and fall at a constant velocity

Question 39

What is the relationship between acceleration and drag forces?

Answer 39

the drag forces increase as the body acelerates
- increasing velocity means drag forces will increase