Forces

Question 1

Distance

Answer 1

How far an object moves

Scalar

Question 2

Displacement

Answer 2

Distance in a direction

Vector

Question 3

Speed

Answer 3

Distance/time

Question 4

Velocity

Answer 4

Displacement/ time

Vector

Question 5

Scalar

Answer 5

Quantity that only has magnitude

Question 6

Vector

Answer 6

Quantity that has magnitude and direction

Question 7

Acceleration

Answer 7

Final velocity-initial velocity/time

-+

Question 8

Forces

Answer 8

Direction of arrows show direction of force
Length proportional to size of force
Arrows touch object

Question 9

Resultant force

Answer 9

Vector sum of all forces acting on object

Question 10

How to calculate resultant forces

Answer 10

Find total of all forces on each side
Take away smaller force from bigger force
If resultant forces=0N
Forces are balanced

Question 11

Newton’s first law

Answer 11

An object will remain at rest or continue to move with a constant velocity unless acted upon with a resultant force

If resultant force=0, forces are balanced

Question 12

Newton’s 2nd law

Answer 12

If the resultant force acting on an object is not zero, all forces are unbalanced
Forces cause masses to accelerate

Speed may change
Direction may change

Question 13

Newton’s 3rd law

Answer 13

Forces exist in pairs

2 objects exert the same force on each other, acting in opposite directions and objects

Question 14

Friction

Answer 14

Occurs between 2 objects because surfaces are rough and contain bumps and hollows
Roughness= force is needed to move 2 objects over each other
Oppose motion

Question 15

Reducing effects of friction

Answer 15

Friction creates heat, wear down surfaces which can damage

Lubricants, bearings, rollers reduce friction and protect surfaces

Question 16

Types of friction

Answer 16

Through air, air resistance

Through liquid, drag

Question 17

Reducing impacts of air resistance

Answer 17

Streamlining, enables air to flow past as easily as possible

Question 18

Effects of friction

Answer 18

Heating

Erosion

Question 19

Uses of friction

Answer 19

Car tyres grip surface

Car rolls because friction force is small, friction is overcome in order to move

Question 20

Weight

Answer 20

A force caused by gravity

Measured in N, not constant, depends on location

Question 21

Jumping out of a plane

Answer 21

Resultant force= vector sum of forces acting on it
RF causes acc
N2L

Question 22

Speeding up

Answer 22

RF=W-A=acc

W-A/m=a

Question 23

Terminal velocity

Answer 23

RF=W-A=0N

N1L

Question 24

Opening parachute

Answer 24

RF/m=-VE/m=-VEm/s

N2L

Question 25

Gliding down

Answer 25

RF=W-A=0N Smaller terminal velocity N1L

Question 26

Landing

Answer 26

RF=-VE | N3L

Question 27

Circular motion

Answer 27

Objects moving around in a circular shape Speed, no change Velocity, constantly changing Resultant force, centripetal force causes acceleration towards center of circle

Question 28

Factors that affect centripetal force

Answer 28

Mass Speed Radius

Question 29

How mass affects centripetal force

Answer 29

Larger mass, larger CF To maintain circular motion, there will be a particular acceleration Higher the mass, larger force needed to maintain acceleration

Question 30

How speed affects centripetal force

Answer 30

Faster the object, larger the CF Object travelling faster covers more distance per second and will change direction by a bigger angle every second Bigger CF needed to maintain bigger acc towards center

Question 31

How does radius affect centripetal force

Answer 31

Smaller radius, larger centripetal force Smaller radius, smaller circumference, smaller distance Complete more of the orbit per second, change direction by a greater angle each second Larger CF needed to get bigger acceleration towards center

Question 32

Space and orbits

Answer 32

Planets orbit sun in elliptical path with sun at focus | Planets are gravitationally attracted to the sun causing this

Question 33

Asteroids

Answer 33

Small belts of rock which orbit sun between Mars and Jupiter

Question 34

Comets

Answer 34

Rock, ice, methane, ammonia a few km in diameter. Orbit sun in eccentric ellipses

Question 35

Universe

Answer 35

Everything in the universe and contains galaxies

Question 36

Galaxies

Answer 36

Contains many stars

Question 37

Artificial satellites

Answer 37

Orbit earth

Question 38

Geostationary satellite

Answer 38

Orbit above equator and take 24hrs to orbit High Used for communications

Question 39

Polar satellite

Answer 39

Orbits longitudinally as Earth spins 6hr orbit Low Weather and crop monitoring

Question 40

Center of mass in regular objects

Answer 40

Along line of symmetry

Question 41

Center of mass for irregular lamina

Answer 41

``` Put in 2 random holes Hang lamina from 1 hole with pin Plumb line on pin Draw line where string has settled Repeat 2,3,4 with other hole Center of mass is where the lines cross ```

Question 42

Pendulum

Answer 42

``` Highest point of swing No KE, highest GPE Lowest point of swing Max KE Min GPE T=1/F ```

Question 43

Stability

Answer 43

An object will become unstable when the line going down from the center of mass passes where the center of mass would meet the ground

Question 44

Factors that center of mass is affected by

Answer 44

Width of base | Height of center of mass

Question 45

Improving stability

Answer 45

Heavy base lowers c of m, harder to knock over | Broader base, harder to knock over

Question 46

Moments

Answer 46

Turning effect of a force No When forces do not line up, rotate Moment=force x distance perpendicular from pivot AM CM, equal, balanced

Question 47

Stretching

Answer 47

``` 2 equally sized forces Act on same object Different forces Forces cancel out Stretch of force is proportional to amount of extension or compression in spring as long as elastic limit has not been exceeded ```

Question 48

Spring constant

Answer 48

How many Newton's are needed to make spring a meter long

Question 49

Elastic

Answer 49

Returns to original shape

Question 50

Plastic

Answer 50

Does not return to original shape

Question 51

Elastic behavior

Answer 51

Extension is proportional to force and material will go back to the original length when we remove the force

Question 52

Plastic behavior

Answer 52

When a force is applied to deform the shape. It stays deformed when the force is removed