Forces, Motion And Energy

Question 1

Resultant force

Answer 1

Whenever two bodies interact, the forces they exert on each other are opposite and equal

Question 2

When a ball falls through fluid

Answer 2

Beggining: stationary, only weight acts on the ball

Middle: increasing speed (resistive force increases as the speed increases, causing the acceleration of the ball to decrease)

End: terminal velocity (weight equals upward resistive force and acceleration is zero)

The arrows level out.

Question 3

Kinetic energy

Answer 3

Movement

Question 4

When a car breaks

Answer 4

The speed decreases and this reduces the kinetic energy. It is convert into other forms of energy.

Question 5

If a mass is dropped

Answer 5

The gravitational potential energy is converted into kinetic energy

Gpe= ke

Gh = 1/2mv2

Question 6

As an object falls through a fluid such as air

Answer 6

It collides with air molecules and pushes them out of the way.

Question 7

When ke strikes the ground

Answer 7

It gets converted into other forms such as heat and sound

Question 8

Work done is equal to

Answer 8

Energy transferred

Question 9

To stop a veichle

Answer 9

Breaking force is needed.

Question 10

Stopping time depends on

Answer 10

Reaction time and braking time

Question 11

Stopping distance depends on

Answer 11

Thinking distance and braking distance

Question 12

When a veichle travels at a steady speed

Answer 12

The frictional forces balance the driving force

Question 13

A drivers reaction time can be affected by

Answer 13

Tiredness, drugs, and alcahol. These will increase the reaction time.

Question 14

A veichle braking distance can be affected by

Answer 14

Adverse road and weather conditions (e.g ice, water or oil on the roads)

And the poor condition of the veichle (defective brakes or no tread on tyers)

Question 15

The breaking distance is also affected by the

Answer 15

Mass and speed of the veichle

Question 16

On a velocity- time graph

Answer 16

The flat bit is the thinking time and the slope is the braking time

Question 17

When a stretching force is applied to an object

Answer 17

It’s shape and size can be altered and the object is said to be deformed

This deformation can be elastic or plastic

Question 18

Elastic deformation

Answer 18

The object will return to its original shape and size, once the force is removed

Question 19

Plastic deformation

Answer 19

The object will not return to its original state and size, once the stretching force is removed

Question 20

When a spring is loaded

Answer 20

It initially undergoes elastic deformation but if the load is increased above its elastic limit, the spring will undergo plastic deformation

Question 21

Extension

Answer 21

The amount by which the spring stretches

Question 22

Hookes law

Answer 22

Provided the stretching force acting on an object does not extend the elastic limit, the extension of the object is directly proportional to the stretching force

Question 23

when something falls

Answer 23

the weight of the object is constant and acts downwards causing the object to fall

as the object falls, it collides with the fluid particles which exert frictional forces (drag) on the object

as the speed of the object increases, it collides with the particles more frequently

frictional forces increase in this way until they balance the weight

when the weight equals the frictional forces, the forces are balanced and the resultant force is zero

no object no longer accelerates

the object continues to fall at its terminal velocity

Question 24

if an object collides with the ground the kinetic energy is converted into

Answer 24

sound and heat energy

Question 25

when the height of an object increases its gpe

Answer 25

increases

Question 26

when an object is dropped its gpe

Answer 26

decreases and its ke increases

Question 27

how to work out the power of someone

Answer 27

record the mass of each person
calculate the weight of each person, using w=mg
calculate the total height of the stairs
record the time taken for someone to run up the stairs
calculate the work done wd=mgh
calculate the power using wd/time taken

Question 28

the slope/ gradient of the graph shows

Answer 28

acceleration

Question 29

area under the graph shows

Answer 29

distance travelled

Question 30

why should you bend your knees when jumping

Answer 30

When we bent our knees on landing, the time of impact increases and reduces the average force exerted during the entire process. This prevents the chance of damage to our body.

Question 31

what does unbalanced force mean

Answer 31

when there is a difference in the forces acting

Question 32

how to work out deceleration

Answer 32

just put a minus in front of the acceleration

Question 33

the gravitational field strength

Answer 33

causes moons to orbit planets
causes the planets to orbit the sun
causes artifical satellites to orbit the earth
causes commits to orbit the sun

Question 34

the universe is

Answer 34

a large collection of billions of galaxies

Question 35

a galaxy is

Answer 35

a large collection of billions of stars

Question 36

planets

Answer 36

orbit the sun
have near circular orbits
the sun is at the centre of a planets orbit
in our solar system, the planets all orbit the sun in the same place
the speed of the planet during the orbit is roughly constant

Question 37

moons

Answer 37

moons orbit planets
moons have near circular orbits
a planet can have many moons. the moons of a planet orbit the planet in the same plane
the speed of the moon during the orbit is roughly constant

Question 38

comets

Answer 38

comets orbit the sun
comets have very elliptical orbits
the sun is at one focus of the elliptical orbit
a comet has an orbit which is not in the same plane as the planets
the speed of the comet increases as the comet approaches the sun and the gravitational field strength increases