Forces and Motion If I were…

1.

Forces and Motion
If I were…

2.

Contents
If I were calculating speed
If I were friction
If I were a skydiver

3. If I were… calculating speed

Describe the formulae for a single object
and relative motion or two objects.

4.

If two objects are moving in opposite directions
along the same line, I can add their speeds together.
If two objects are moving in the same directions
along the same line, I can subtract their speeds.
Speed =
distance ÷ time
If I were…
calculating speed
S=
d÷t
I could be measured in m/s,
mph (miles/h) or km/h.
I could use a formula triangle and
cover the part I want to calculate.
d
S t

5. If I were… friction

Describe and explain the effects
on an object (uses and problems).

6.

I would be useful for gripping objects to a surface for
creating or stopping movement e.g. bicycle tyres or brakes.
I would restrict how fast something can move
in air by acting as air resistance (drag).
If I were…
I would waste energy
by generating heat.
friction
I would act opposite
to movement.
I would restrict how fast something can
move in water by acting as water resistance.
Objects would need to be
streamlined to reduce my effect.

7. If I were… a skydiver

Describe and explain the forces
and effects on movement
throughout a jump.

8.

When I first jump out of the plane,
I would fall fast and accelerate.
When I first jump out of the plane, my
weight would be the greatest force.
As I increase in speed the air resistance
(drag) acting on me would increase.
If I were…
a skydiver
Air resistance and the weight would
become equal and I would continue
to fall, but at a steady speed. This is
terminal velocity.
When I open my parachute, the
air resistance would increase.
As the air resistance acts on my parachute, I would slow down. (The open parachute has a large surface area which
increases the air resistance. This results in the forces becoming unbalanced and causes the parachutist to slow down.)
When I land, my weight would be balanced by the
reaction force from the ground and I would stop.