Topic 2 - Motion and Forces

Question 1

Scalar quantity

Answer 1

Physical quantities with magnitude only

Question 2

Vector quantity

Answer 2

Physical quantities with magnitude and direction

Question 3

Scalar examples

Answer 3

Speed, distance, mass, energy, temperature, time

Question 4

Vector examples

Answer 4

Force, velocity, displacement, weight, acceleration, momentum

Question 5

Velocity

Answer 5

Speed in a given direction

Question 6

Speed(m/s)=

Answer 6

Distance(m)/time(s)

Question 7

Distance(m)=

Answer 7

Average speed(m/s) x time(s)

Question 8

How to interpret distance/time graphs

Answer 8

Gradient at a given point gives speed at that point. Use speed equation to calculate average speed by using total distance and total time on the graph.

Question 9

Acceleration(m/s2)=

Answer 9

Change in velocity(m/s) / time(s)

Question 10

Uniform acceleration is

Answer 10

A constant acceleration. Acceleration due to gravity is uniform for objects in free fall and its roughly 10 m/s2.U

Question 11

Uniform acceleration equation

Answer 11

v(final velocity)2 - u(initial velocity)2 = 2 x a(acceleration) x X(Distance)

Question 12

How to interpret velocity/time graphs

Answer 12

Gradient at a point is the acceleration. Steeper the graph, higher the acceleration. The distance under the graph shows distance travelled in that time period.

Question 13

Trolley motion practical

Answer 13

Connect light gates along a ramp , with a trolley connected to a string at the top. At the end of the string hang a mass on a hook. Let the trolley go and use the light gates speed and time measurements to calculate acceleration

Question 14

Other methods of determining the speed of objects

Answer 14

Rolling tape measure or stopwatch for walking speed. Video and frames per second method

Question 15

Typical Walking speed

Answer 15

1.4 m/s

Question 16

Typical running speed

Answer 16

3 m/s

Question 17

Typical cycling speed

Answer 17

5.5 m/s

Question 18

Typical car in city speed

Answer 18

13 m/s

Question 19

Typical aeroplane speed

Answer 19

250 m/s

Question 20

Typical car on motorway speed

Answer 20

31 m/s

Question 21

Typical train speed

Answer 21

55 m/s

Question 22

Typical wind speed

Answer 22

5-20 m/s

Question 23

Typical speed of sound in air

Answer 23

340m/s

Question 24

Typical ferry speed

Answer 24

15 m/s

Question 25

Newtons first law

Answer 25

If the resultant force on a stationary object is 0, the onject will remain stationary. If the resultant force on a moving object is 0, it will carry on at the same velocity.

Question 26

Newtons second law

Answer 26

Force and acceleration are directly proportional. Acceleration is inversely proportional to the object mass.

Question 27

F=

Answer 27

m x a

Question 28

Weight(N) =

Answer 28

mass(kg) x gravitational field strength(N/kg)

Question 29

Higher gravitational field strength leads to

Answer 29

Higher weight. Meaning weight changes in different locations

Question 30

How does speed and velocity change in an object moving in a circular motion

Answer 30

Speed stays constant, whilst velocity is always changing due to constant changes in direction.

Question 31

What is the force that keeps an object moving in a circular motion

Answer 31

The centripetal force, which causes a resultant force on the object that keep it accelerating

Question 32

Inertial mass

Answer 32

A measure of how difficult it is to change the velocity of an object. m = F/a

Question 33

Newtons third law

Answer 33

When two objects interact, the forces they exert on each other are equal and opposite.

Question 34

Newtons third law in collisions means that

Answer 34

If two things collide, they will accelerate depending on their mass. The higher the mass the less the forces will make it accelerate. This also explains conservation of momentum.

Question 35

Newtons third law in equilibrium reactions

Answer 35

Gravity leads to weight pulling an object down, and the object pulls back up on the earth.

Question 36

Momentum is

Answer 36

A property that all moving objects have that shows how hard it is to stop the object.

Question 37

Momentum kg m/s (P) =

Answer 37

Mass(kg) x Velocity(m/s)

Question 38

Conservation of momentum

Answer 38

The total momentum before is equal to the total momentum after in a closed system

Question 39

Changes in momentum occur from?

Answer 39

A force acting on an object over a period of time. Newtons second law explains this.

Question 40

Force(N) =

Answer 40

Change in momentum(kg m/s) / Time(s)

Question 41

Ruler drop experiment

Answer 41

Tests reaction time. Hold the bottom of the ruler in line with a persons hand. Without warning drop the ruler and the other has to catch it as fast as possible. Calculate reaction time from the distance and acceleration. Typical time between 0.2-0.6s.

Question 42

Stopping distance =

Answer 42

Thinking distance+Braking distance

Question 43

Thinking distance

Answer 43

Distance car travels in the time between when the drivers sees the stimulus and applies the brakes.

Question 44

Braking distance

Answer 44

Distance taken to stop once the brakes have been applied

Question 45

Driver reaction time affects

Answer 45

Thinking distance. Inccreased by tiredness, alcohol, drugs and distractions

Question 46

Speed of vehicle affects

Answer 46

Thinking distance because it increases distance travlled during reaction time and braking distance because it takes longer to stop

Question 47

Mass of car affects

Answer 47

Braking distance because it increases the force needed to stop the car

Question 48

State of vehicle brakes affect

Answer 48

Braking distance because if they are worn they wont be able to brake with as much force.

Question 49

State of road affect

Answer 49

Braking distance becuase there may be decreased friction leading to longer for it to stop

Question 50

Large decellerations are dangerous because

Answer 50

The less time the change in momentum occurs over, the higher the force. This means that there is more chance of injury from more forceful collisions.

Question 51

As speed increases, thinking distance... and braking distance...

Answer 51

Thinking distance increases at the same rate, and braking distance increases by the scale factor power 2.

Question 52

Energy in the cars kinetic store=

Answer 52

Work done by the brakes

Question 53

(1/2) x (m) x (v power 2) =

Answer 53

F x d