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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
+
2. Two vectors in the
opposite direction
3N
4N
7N
=
+
3N
1N
=
3. Two vectors at right angles to each other
1st
2
work out the size :
R=
2
= 5 m/s
3 + 4
R
4 m/s
2st work out the direction : angle a = Tan
Opp
adj
a
3 m/s
-1
= Tan
-1
4/3 = 53 degees
Equations of Motion (SUVAT)
1
v = u + at
2
Don’t need to remember or
rearrange
s = (u + v) t
2
3
2
2
v = u + 2as
Don’t need to remember but
could rearrange
4
2
s = ut + ½ at
u = speed at the start of question, v speed at the end of the question
S = distance travelled, a = acceleration, t = time
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
2
u2
=
+
2 as
move the u2 over (positive becomes minus)
v
2
v2
u2
=
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