Combined Physics - P5 Forces Flashcards

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1
Q

What two things does a force arrow show?

A
  1. The length of the arrow shows the size of the force.
  2. The direction of the arrow shows the direction of the force.
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2
Q

Give some examples of non-contact forces

A
  • Gravitational force
  • Electrostatic force
  • Magnetic force
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3
Q

What is a ‘resultant force’?

A

The sum of all forces acting on an object

(the overall force acting on an object)

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4
Q

What equation links force, spring constant and extension?

A

Force = spring constant x extension

F = k e

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5
Q

Give some examples of contact forces

A
  • Friction
  • Air resistance
  • Tension
  • Normal contact force
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6
Q

What are the units for:

a) gravitational field strength
b) weight
c) mass

A

a) N/kg
b) N
c) kg

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7
Q

What is the equation that links work done, force and distance?

A

Work done = force x distance

W = F s

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8
Q

What equation links weight, mass and gravitational field strength?

A

Weight = mass x gravitational field strength

W = m g

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9
Q

Why type of energy is stored in a spring that is stretched or compressed?

A

Elastic potential energy

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10
Q

What happens to the temperature of an object experiencing friction?

A

Temperature increases

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11
Q

What is the name of an object that:

a) will return to its original shape after being deformed
b) will not return to its original shape after being deformed

A

a) elastic
b) inelastic

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12
Q

What is the relationship between force and extension of an elastic object?

A

Directly proportional

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13
Q

What happens to air resistance as speed increases?

A

As speed increases, air resistance increases.

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14
Q

What are typical speed values for someone walking, running and cycling (m/s)?

A
  • Walking 1.5 m/s
  • Running 3 m/s
  • Cycling 6 m/s
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15
Q

What is the speed of sound?

A

340 m/s

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16
Q

How many forces need to to be applied to this spring to stretch or compress it?

A

Two forces (e.g. one at either end)

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17
Q

What equation links acceleration, final velocity, initial velocity and time?

A
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18
Q

What equation links distance travelled, speed and time?

A

Distance travelled = speed x time

s = v t

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19
Q

Why does a falling object reach terminal velocity?

A
  • The resultant force on the object is zero.
  • Forces of weight and air resistance are balanced.
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20
Q

Name the point on the graph labelled ‘X’

A

Limit of proportionality

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21
Q

Describe the motion in the following distance-time graph at points a, b, c and d.

A

a) constant speed
b) stationary
c) accelerating
d) decelerating

22
Q

If you wanted to investigate how mass affects acceleration, what part of the equipment would you change?

A

The mass of the trolley (by adding more masses to the trolley).

23
Q

Which part of the equipment measures acceleration?

A

Light gate

24
Q

If you wanted to investigate how force affects acceleration, what part of the equipment would you change?

A

The force pulling the trolley (by adding more masses to the hook).

25
Q

What is the equation for Newton’s Second Law that links force, mass and acceleration?

A

Force = mass x acceleration

F = m a

26
Q

Give three factors that can affect braking distance.

A
  • Road conditions
  • Weather conditions: wet / icy roads
  • Vehicle conditions: condition of brakes / tyre tread depth
27
Q

What equation links momentum, mass and velocity?

A

Momentum = mass x velocity

p = m v

28
Q

What happens if a car undergoes a large deceleration?

A

Brakes overheating / loss of control

29
Q

Describe the motion of a moving car experiencing balanced forces.

A

Keep moving at a constant speed

30
Q

Describe the motion of a moving car experiencing unbalanced forces.

A

The car will change speed (either accelerate or decelerate)

31
Q

Describe the motion of a stationary car experiencing balanced forces.

A

The car will remain stationary.

32
Q

Describe the motion of a stationary car experiencing unbalanced forces.

A

The car will accelerate.

33
Q

What are typical everyday speeds for cars, trains and planes?

A
  • Car 25 m/s
  • Train 55 m/s
  • Plane 250 m/s
34
Q

What is stopping distance?

A

The sum of the thinking distance and the braking distance

35
Q

What is braking distance?

A

The distance covered during the braking force.

36
Q

What are ‘typical’ reaction times?

A

0.2 s to 0.9 s

37
Q

What is Newton’s Third Law?

A

Whenever two objects interact, the forces they exert on each other are equal in size and opposite in direction.

38
Q

What is thinking distance?

A

The distance covered during the driver’s reaction time.

39
Q

How does speed affect stopping distance?

A

Stopping distance increases with speed.

40
Q

Give three factors that can affect a driver’s reaction time.

A
  • Tiredness
  • Drugs
  • Alcohol
41
Q

What is work done the same as?

A

Energy transferred

42
Q

If your mass on Earth is 50 kg, what would be your mass on the moon?

A

The same, 50 kg.

Your mass does not change.

43
Q

What are the units for:

a) force
b) acceleration
c) weight
d) mass

A

a) N
b) m/s2
c) N (weight is a force)
d) kg

44
Q

Name the forces acting on the book.

A
45
Q

Calculate the resultant force on the box

A

0 N (there is no resultant force)

46
Q

Calculate the resultant force on the box.

A

2N to the left

47
Q

Describe the experiment to investigate how force affects the extension of the spring.

A
  • Measure the starting length of the spring using the ruler.
  • Add one 10 g mass, measure the extension of the spring using the ruler.
  • Repeat 5 times, each time adding one 10 g mass and measuring the extension of the spring.
48
Q

Higher Q. What is inertia?

A

The tendency of objects to continue in their state of rest / uniform motion

49
Q

Higher Q. How can the displacement of an object (the distance travelled) be calculated from a velocity-time graph?

A

The area under a velocity-time graph

50
Q

Higher Q. What is inertial mass?

A

A measure of how difficult it is to change the velocity of an object.

51
Q

Higher Q. How can the motion of an object in a circle be described?

A

Constant speed but changing velocity