Vector & Scalar quantities

Mass is a scalar quantity – It has a size (example 100kg)

But no direction

Velocity is a vector quantity – It has a size and a direction

(example 5 m/s to the right)

Force is a vector quantity – It has a size and a direction

(example 100N downwards)

Adding vectors

1. Two vectors in the same direction

4N + 3N

=7N

2. Two vectors in the opposite direction

4N + 3N

=

1N

3. Two vectors at right angles to each other

3 m/s

4 m/s

1st work out the size : R = 3 + 4

R

2 2 = 5 m/s

2st work out the direction : angle a = Tan Opp

adj

= Tan 4/3 = 53 degees

a

-1

-1

Equations of Motion (SUVAT)

v = u + at

s = (u + v) t 2

Don’t need to remember or rearrange

v = u + 2as 2 2

s = ut + ½ at 2

Don’t need to remember but could rearrange

u = speed at the start of question, v speed at the end of the question

S = distance travelled, a = acceleration, t = time

1

2

3

4

How to answer SUVAT questions

1. Write out SUVAT and write down any values you are given in the question

S=

U=

V =

a=

t =

2. Put the numbers into the formula and work out the answer. You will be given the formula

Re arranging animation

1. A question that needs equation 3 that asks you to find the distance (s): You must get s by itself

v u a s22 2= +

move the u2 over (positive becomes minus)

v 2v u22 = 2as

Move 2a over to the other side (multiply becomes divide)

v2 - u2 =

Horizontal and vertical motion

1. They are independent of each other. (one does not affect the other)

Horizontal velocity is constant (ignoring air resistance)

Vertical velocity is increasing due to gravity