topic 2: forces and motion

Question 1

Differences between vector and scalar

Answer 1

• Vectors have magnitude and direction

- scalars have just magnitude

Question 2

Examples of vectors and scalars

Answer 2

vectors
-velocity, force, acceleration etc.
Scalars
-mass, speed,distance etc.

Question 3

Displacement time graphs

Answer 3

• Horizontal lines means stationary

- area under line = nothing

Question 4

How to determine average speed

Answer 4

• work out TOTAL distance travelled
• find time taken for WHOLE journey
• use speed = distance/ time

Question 5

Determine speed using light gates

Answer 5

• set up one at beginning and end
• measure distance between them
• As soon as object passes through first measure time taken to reach second light gate
• use speed = distance/time

Question 6

Newton’s first law

Answer 6

• object has constant velocity unless acted on by resultant force– if resultant force acts on it, will accelerate and velocity will change
• direction or speed of object will change
  (or both)

– if no resultant force, no acceleration, moving at constant velocity, object is at rest (no speed)

Question 7

Newton’s Second Law

Answer 7

force (N) = mass ( kg)x acceleration ( m/s )

Question 8

Newton’s Third law

Answer 8

• Every action has an equal and opposite reaction

Question 9

momentum equation ( kg m/s )

Answer 9

momentum= mass (kg) x velocity ( m/s)

Question 10

average human reaction time

Answer 10

average human reaction time = 0.25 sec