7- Motion

Question 1

Define speed

Answer 1

The rate of change of distance

Scalar

Question 2

Define displacement

Answer 2

The (shortest) distance between 2 points in a given direction
(Vector)

Question 3

Define velocity

Answer 3

The rate of change of displacement

Vector

Question 4

Define acceleration

Answer 4

The rate of change of velocity

Scalar

Question 5

Define scalar and give examples

Answer 5

A scalar is a physical quantity that includes only magnitude.

Question 6

Define vector and give examples

Answer 6

A scalar is a physical quantity that includes magnitude and direction.

Question 7

Vector or scalar?
Displacement 
Distance 
Charge 
volume
Force 
Velocity 
Torque 
Mass
Speed 
Energy 
Momentum 
Acceleration

Answer 7

Vector:
Displacement 
Force
Velocity 
Acceleration 
Momentum 
Torque 

Scalar:
Distance 
Speed
Mass
Energy 
Volume
Charge

Question 8

Define torque

Answer 8

Torque is how much a force acting on an object causes that object to rotate.

Question 9

How do you find resultant vector

Answer 9

Draw vectors head to tail then connect the first tail and the last head to create 1 joining line.
Use Pythagoras for magnitude of vector. Use SOHCAHTOA to find angles.

Remember- Sin for stretch. Cos for compression. (Rubber band)

Question 10

What are the four equations of uniform motion? (SUVAT)

Answer 10

S= 1/2(U+V)t

Question 11

How does a SUVAT equation relate to y=mx+c

Answer 11

y=mx+c

V=at +U

Question 12

What does SUVAT stand for and what’s the rule when using it

Answer 12

S= displacement 
U= initial velocity 
V= final velocity 
A= acceleration 
T= time 

It has to be along the same plane

Question 13

Define mass

Answer 13

A measure of the amount of substance present, set by the number and type of atoms present

Question 14

Define Weight

Answer 14

The force acting on an object with mass when placed in a gravitational field.
W= mg
(Kg)

Question 15

What’s the equation for drag force?

Answer 15

Drag force= 1/2 * (density of fluid its falling through)* (velocity)^2
(drag coefficient) (face area of front of object towards direction of travel)

=1/2 * ρ * v^2 * Cd * A

Question 16

Define power

Answer 16

The rate at which energy is transferred (work is done)

Question 17

What are the equations for power?

Answer 17

P= (delta)E/(delta)t

Power= energy/time

P= FV

Power= force*velocity

Question 18

What’s the equation for work done?

Answer 18

Work done= force*distance

Question 19

What’s the difference between elastic collision and inelastic collisions?

Answer 19

In elastic collisions momentum AND kinetic energy is conserved

In inelastic collisions momentum is conserved but kinetic energy is not (some energy is lost to its surroundings)

Question 20

What’s the equation for momentum and what’s it measured in?

Answer 20

P=mv

Momentum= mass* velocity

(Kgms^-1) or Ns

Question 21

What are the equations for kinetic energy and what’s it measured in?

Answer 21

Ek= 1/2mv^2

Ek= p^2/2m
= (momentum)^2 / 2*(mass)

(KJ)

Question 22

what is impulse, whats it measured in and what’s the equation for it?

Answer 22

impulse the change in momentum (mV-mU) since p=mv
measured in Ns
F=(mV-mU)/t

Question 23

what can a force-time graph give us

Answer 23

the area under the graph line of a force-time graph gives us the impulse.
If force is on y-axis, time on x-axis.

Question 24

what is the relationship between the gravitational potential something has and its work done?

Answer 24

the gravitational potential an object has is equal to the work done in moving that object up to that height.

Question 25

what is the relationship between the kinetic energy something has and its velocity?

Answer 25

If you multiply the speed by 2, the Ek will be multiplied by 4. If you multiply the speed by 3, the Ek will be multiplied by 9. You square it. (since its mv^2)

Question 26

what is newtons first law?

Answer 26

'an object at rest remains at rest, and an object in motion remains at constant velocity unless a resultant force acts' This is known as inertia.

Question 27

what is newtons second law?

Answer 27

'the acceleration of an object is directly proportional to the magnitude of the resultant force (in the same direction), and inversely proportional to the mass of the object' F=ma, a∝F, a∝1/m

Question 28

how do you find one newton

Answer 28

one newton is the resultant force required to accelerate a mass of 1kg by 1ms^-1

Question 29

what is newtons third law?

Answer 29

'every action has an equal and opposite reaction' OR 'If body A exerts a force on body B, then body B exerts an equal size force in the opposite direction on body A'

Question 30

what are the 5 rules for newtons 3rd law pairs of forces

Answer 30

1. same type of force 2. same magnitude 3. act along the same line of action 4. act in opposite directions 5. act on 2 different bodies

Question 31

how do you calculate efficiency

Answer 31

efficiency = (useful energy out/total energy in) *100

Question 32

how do you calculate absolute uncertainty

Answer 32

add ± 1 of the smallest significant figure.

Question 33

how do you calculate percentage uncertainty

Answer 33

Percentage Uncertainty = (Absolute Uncertainty / Measured Value) x 100

Question 34

What unit is the same as the newton?

Answer 34

kg ms^-2

Question 35

what base (SI) unit can be used for power

Answer 35

kg m^2 s^-3

Question 36

how can distance traveled/displacement be found from a velocity-time graph?

Answer 36

its the area under a velocity-time graph

Question 37

how can velocity be found from a displacement-time graph?

Answer 37

its the gradient of a displacement-time graph

Question 38

how can acceleration be found from a velocity-time graph?

Answer 38

its the gradient of a velocity-time graph