Physics- Motion

Question 1

Speed (m/s)

Answer 1

How fast something is moving regardless of direction

Question 2

Displacement (s)

Answer 2

How far an object’s travelled from its starting point in a given direction.

Question 3

Velocity (v)

Answer 3

The rate of change of an object’s displacement (its speed in a given direction)

Question 4

Acceleration (a)

Answer 4

Rate of change of an objects velocity

Question 5

Acceleration formula

Answer 5

Acceleration is the rate of change of velocity.
1.)a=(v-u)/t so v=u + at
2.)s= average velocity x time acceleration constant, the average velocity is average initial and final so (u+v)/2 x t
3.) Sub expression for v from equation 1 into 2 gives s=(u + u + at) x t /2
s = ut + 1/2at^2
4.)derive a = (v-u)/2 multiply by s, s= (u+v)/2 x t gives as=(v-u)/2 x (u+v)t/2 ts cancel so 2as= (v-u)(v+u) or 2as=v^2 -uv+uv -u^2
v^2=u^2 + 2as

Question 6

Uniform Acceleration

Answer 6

Constant Acceleration

Question 7

Suvat Equations

Answer 7

V=u+at
S=vt-1/2at^2
S=ut+1/2at^2
S=1/2(u+v)t
V^2=u^2+2as

Question 8

Average Speed

Answer 8

= Total distance/ Total time

Question 9

Average Velocity

Answer 9

= Total displacement/ Total time

Question 10

Instantaneous Velocity

Answer 10

Velocity at a particular point in time.
The gradient of the tangent in a displacement/time graph.

Question 11

Acceleration

Answer 11

The rate of change of velocity

Question 12

The area under a velocity time graph

Answer 12

Is the displacement

Question 13

If the acceleration is in the direction of motion

Answer 13

It is positive.

Question 14

If the acceleration is opposite to the direction of motion

Answer 14

it is negative.(deceleration)

Question 15

Vertical acceleration

Answer 15

9.81ms^-2

Question 16

If an object is projected upwards

Answer 16

An acceleration of -9.81ms^-2 acts upon it. (gravity)

Question 17

Give the manual timing PAG method to determining g.

Answer 17

Drop a marble form different heights,
record the time it takes to reach the ground.
Measure the height, h with a ruler,
Measure the time,t, with a stopclock or a video (phone)
Plot a graph of the h against t^2
Use SUVAT s+ut+1/2at^2
Derive into S=1/2at^2
h=1/2 gt^2

TO REDUCE PERCENTAGE UNCERTAINTIES
Make sure that h is as large as impossible,
Use a trapdoor or electro magnet so the time is consistently and height remains the same as human error is not involved. Certainty ^^

Question 18

Light gate Method

Answer 18

2 light gates
Measure initial velocity and light gate 2 to measure final
measure distance between two with ruler v^2=u^2+2as

Question 19

Stopping distance

Answer 19

= thinking distance + braking distance

Question 20

Thinking distance

Answer 20

defined as the distance travelled by the vehicle from the moment a driver spots a hazard to the time they press the brake pedal

Question 21

Braking distance

Answer 21

Distance from the moment the driver presses the brake pedal to the moment the car stops.

Question 22

Braking distance equation

Answer 22

v^2=u^2+2as
0=u^2+2aSb

Sb= -u^2/2a

(a negative because its deceleration)

Question 23

Thinking distance equation

Answer 23

speed x time