Forces and Motion

Question 1

What is the equation for speed?

Answer 1

speed = distance/time

Question 2

What is the equation for weight?

Answer 2

weight = mass x gravity

Question 3

What is the equation for acceleration?

Answer 3

acceleration = change in velocity/time

Question 4

What is the relationship between force, mass, and acceleration?

Answer 4

force = mass x acceleration

Question 5

What does the gradient in a distance time graph represent?

Answer 5

speed

Question 6

What does the gradient in a velocity time graph represent?

Answer 6

acceleration

Question 7

What does a curving line represent on a distance time graph?

Answer 7

acceleration/ deceleration

Question 8

What does a curving line represent on a velocity time graph?

Answer 8

increasing acceleration / deceleration

Question 9

What does a horizontal line represent on a distance time graph?

Answer 9

stopped

Question 10

What does a horizontal line represent on a velocity time graph?

Answer 10

steady speed

Question 11

What IS acceleration?

Answer 11

the rate of increase of velocity with time

Question 12

Why do objects reach terminal velocity?

Answer 12

when an object has the balanced forces of air resistance and weight on it. It falls at a constant speed. The two examples are a sky diver and sycamore seeds.

Question 13

How do you find distance from a velocity time graph?

Answer 13

area under graph

Question 14

What is the unit for velocity?

Answer 14

m/s

Question 15

What is the unit for acceleration?

Answer 15

m/s2

Question 16

What is the unit for force?

Answer 16

Newtons

Question 17

What is the unit for momentum?

Answer 17

kg m/s

Question 18

What is the unit for volume?

Answer 18

m3

Question 19

What is the fancy unit for temperature?

Answer 19

Kelvin (-273°C)

Question 20

What is the difference between a vector and a scalar quantity?

Answer 20

a vector quantity has both direction and magnitude, where as a scalar quantity just has magnitude.

Question 21

What IS friction?

Answer 21

the force which opposes motion

Question 22

Use ideas about molecules to explain how pressure is caused inside an object.

Answer 22

Any three of
MP1. idea of (continuous) random
movement;
MP2. collisions / impact/eq;
MP3. with (inside) walls;
MP4. idea that force is produced (by
bombarding molecules);
MP5. idea of pressure as force on an
area;

Question 23

What is the equation for gravitational potential energy?

Answer 23

gravitational potential energy = mass x gravity x height

Question 24

What is the equation for refractive index?

Answer 24

n = sin i/ sin r

Question 25

What is Newton's third law of motion?

Answer 25

for every action, there is an equal and opposite reaction

Question 26

What does stopping distance consist of?

Answer 26

thinking distance = braking distance

Question 27

What 2 things affect thinking distance?

Answer 27

- speed | - state of driver (eg. old age, tiredness, dugs, alcohol, inexperience?

Question 28

What 4 things affect breaking distance?

Answer 28

- speed - mass of vehicle - quality of brakes - grip (road surface, weather, tyres)

Question 29

What is the equation for momentum?

Answer 29

momentum = mass x velocity

Question 30

What is the unit for momentum?

Answer 30

kg m/s

Question 31

Momentum before and momentum after are...

Answer 31

equal

Question 32

What is the relationship between force, momentum and time?

Answer 32

force = change in momentum/time

Question 33

How does a crumple zone help?

Answer 33

increases the time for the change in momentum to happen, therefore reducing the force on the car.

Question 34

What is the equation for moments?

Answer 34

moment = force x distance

Question 35

What is the unit for moments?

Answer 35

Newton meters (Nm)

Question 36

Where does the weight of a body act on an object?

Answer 36

centre of gravity

Question 37

What is the principle of moments for a balanced object?

Answer 37

total anticlockwise moments = total clockwise moments | - if this is not true, there will be a resultant movement and the object will turn

Question 38

What is Hooke's law?

Answer 38

extension is directly proportional to force

Question 39

What is elastic limit? What happens past it?

Answer 39

when a material stops obeying hooke's law. If the force is increased past the elastic limit, the material will be permanently stretched, and will not return to its original shape.

Question 40

Elastic behaviour is shown when...

Answer 40

a material returns to its original shape after elastic deformation.

Question 41

Is force a scalar or vector quantity?

Answer 41

vector

Question 42

Our solar system is part of our...

Answer 42

galaxy

Question 43

What is a galaxy?

Answer 43

a huge collection of stars

Question 44

What is the universe?

Answer 44

a large collection of billions of galaxies`

Question 45

What causes orbits?

Answer 45

gravity pulls the objects inwards towards the planet/star, as it is trying to constantly change direction.

Question 46

How do planets obit?

Answer 46

slightly elliptically

Question 47

Two things in orbit of the earth

Answer 47

the moon, artificial satellites

Question 48

In orbits, the further away an object is from the thing it's orbiting

Answer 48

the weaker the gravity and the force of attraction

Question 49

How do comets obit?

Answer 49

very elliptically

Question 50

What is a geostationary satellite and what is it useful for?

Answer 50

has an orbital period of exactly one day, useful for communications.

Question 51

Describe an experiment to investigate motion

Answer 51

- toy car on a ramp using light gates to find the car's average speed - connect light gates to computer and repeat to make it more reliable - to calculate average speed of car divide distance between light gates by time taken - you could change mass of car, different materials for friction, change ramp to see acceleration due to gravity, angle of ramp, different cars

Question 52

Describe an experiment to investigate terminal velocity

Answer 52

- sycamore seeds - measure mass and wing length of different seeds - use seeds with either same wing length or same mass to keep variables constant - drop from same height and record time (higher = better cos improves accuracy) - repeat and find average - draw graph of wing length against time to show relationship between seed size and terminal velocity

Question 53

Why are sycamore seeds used when investigating terminal velocity?

Answer 53

they have a small weight and large surface area so reach terminal velocity quickly