Speed and Acceleration

Question 1

What is a scalar quantity?

Answer 1

A quantity that only has magnitude (size).

Question 2

Give five examples of scalar quantities.

Answer 2

Mass, time, distance, volume, density.

Question 3

What is a vector quantity?

Answer 3

A quantity that has both magnitude and direction.

Question 4

Give four examples of vector quantities.

Answer 4

Force, acceleration, velocity, displacement.

Question 5

What is the difference between distance and displacement?

Answer 5

• Distance: The total path traveled between two points.
• Displacement: The shortest straight-line distance between two points.

Question 6

What is the formula for average speed?

Answer 6

Averagespeed = Totaltime / Totaldistance
​

Question 7

How can you find average speed from a graph?

Answer 7

Use the gradient:
(𝑦2− 𝑦1) / (𝑥2 − 𝑥1)
(riseoverrun)

Question 8

What is maximum speed?

Answer 8

The highest speed recorded, found by identifying the steepest straight line on a graph.

Question 9

What is instantaneous speed?

Answer 9

Speed at a specific moment in time.

Question 10

How do you find instantaneous speed from a graph?

Answer 10

Draw a tangent to the curve and measure its gradient.

Question 11

What is the formula for acceleration?

Answer 11

a = (v−u) / t
where:
* a = acceleration
* 𝑣 = final velocity
* 𝑢 = initial velocity
* 𝑡 = time

Question 12

What is increasing acceleration? Give an example.

Answer 12

Acceleration that increases at an increasing rate.
* Example: 1𝑚/𝑠, 3𝑚/𝑠, 7𝑚/𝑠 (+2,+4)

Question 13

What is decreasing acceleration? Give an example.

Answer 13

Acceleration that slows down over time.

• Example: 1𝑚/𝑠, 5 𝑚/𝑠, 7 𝑚/𝑠 (+4, +2)
• Occurs in cars reaching terminal velocity.

Question 14

What is constant uniform acceleration? Give an example.

Answer 14

Acceleration that stays the same over time.
* Example: 1𝑚/𝑠, 3 𝑚/𝑠, 5 𝑚/𝑠 (+2, +2).

Question 15

What is constant deceleration? Give an example.

Answer 15

Velocity decreases at a constant rate.
* Example: 10 𝑚/𝑠, 7 𝑚/𝑠, 4 𝑚/𝑠 (−3, −3)

Question 16

What does a horizontal line on a speed-time graph mean?

Answer 16

Constant velocity (speed stays the same over time).

Question 17

How do you calculate distance from a speed-time graph?

Answer 17

Find the area under the graph.

Question 18

What formula do you use for a triangle’s area?

Answer 18

1/2 × Base × Height

Question 19

What formula do you use for a rectangle’s area?

Answer 19

Length × Width

Question 20

What formula do you use for a trapezium’s area?

Answer 20

1/2 × (Base 1+ Base 2) × Height

Question 21

How do you estimate the area under a curved speed-time graph?

Answer 21

• Find the midpoint of the curve.
• Divide the area into two shapes.
• Approximate each area and sum them.

Question 22

What is free-fall motion?

Answer 22

Motion under the effect of gravity only.

Question 23

What is the acceleration due to gravity on Earth?

Answer 23

9.8𝑚/𝑠^2

(use 10𝑚/𝑠^2
in exams).

Question 24

What happens to speed and acceleration in free fall?

Answer 24

• Speed increases as the object falls.
• Acceleration remains constant at 9.8 𝑚/𝑠^2

Question 25

Does mass affect free fall?

Answer 25

No, all objects fall at the same rate when air resistance is ignored.

Question 26

What does a straight, diagonal line on a distance-time graph mean?

Answer 26

Constant speed.

Question 27

What does a horizontal line on a speed-time graph mean?

Answer 27

Constant velocity (no acceleration).

Question 28

What does a curve on a distance-time graph mean?

Answer 28

Changing speed (acceleration or deceleration).

Question 29

What does a downward-sloping speed-time graph mean?

Answer 29

Deceleration (slowing down).

Question 30

What happens when an acceleration-time graph is a horizontal line above zero?

Answer 30

Constant acceleration.

Question 31

What information can you extract from a velocity–time graph?

Answer 31

1. The gradient (slope) of a velocity–time graph gives the acceleration 2. The area under the curve represents the displacement of the object.

Question 32

How do you determine instantaneous velocity using a graph?

Answer 32

Instantaneous velocity is found by drawing a tangent at the point of interest on a velocity–time graph; the gradient of this tangent line represents the instantaneous velocity.

Question 33

What are the basic kinematic equations that are useful in motion analysis?

Answer 33

Common equations include: * 𝑣 = 𝑢 + 𝑎𝑡 * 𝑠 = 𝑢𝑡 + (1/2)𝑎𝑡^2 * 𝑣^2 = 𝑢^2 + 2𝑎𝑠 where 𝑢 is initial velocity, 𝑣 is final velocity, 𝑎 is acceleration, 𝑠 is displacement, and 𝑡 is time.

Question 34

Why is vector addition important when dealing with velocity and displacement?

Answer 34

Because velocity and displacement are vector quantities (having both magnitude and direction), using vector addition helps in accurately determining the overall effect when combining movements in different directions.