Forces Flashcards

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1
Q

As mass increases, velocity…

A

Increases

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2
Q

What is the difference between a vector and scalar quantity?

A

A vector quantity has magnitude AND DIRECTION
A scalar quantity has only magnitude

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3
Q

What is the resultant force?

A

The result of all the forces acting on the object

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4
Q

True or false: friction does NOT oppose motion

A

False: friction does oppose motion

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5
Q

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

A

F = ma
Force = mass x acceleration

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6
Q

What is the relationship between weight, mass and gravitational field strength?

A

W = mg
Weight = mass x gravitational field strength

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7
Q

Thinking + braking distance

A

= stopping distance

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8
Q

What affects the thinking distance?

A

Alcohol/drugs
Speed
Tiredness

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9
Q

What affects braking distance

A

Road condition (wet or icy)
Car condition (brakes)
Mass of car
Speed

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10
Q

Describe the forces acting on falling objects (and explain why falling objects reach a terminal velocity)

A
  1. At the start there is only weight acting downwards.
  2. Therefore there is a large resultant force downwards. Since F = ma there is a large acceleration for the same mass.
  3. As the skydiver speeds up (/accelerates), air resistance (upwards) increases.
  4. Eventually the downward weight balances the upward air resistance
  5. Therefore the resultant force is zero. Since F = ma acceleration is zero for the same mass and they travel at a constant speed or terminal velocity.
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11
Q

Hooke’s law (spring/elastic band and weight experiment)
When force increases, extension…

A

Increases

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12
Q

Linear is…

A

Straight line

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13
Q

Non-linear is…

A

Curved line

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14
Q

The straight line through the origin on force extension graphs…

A

Obey Hooke’s law

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15
Q

The non-linear part of force extension graphs…

A

Does not obey Hooke’s law

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16
Q

Where the line stops on force extension graphs is the…

A

Elastic limit - the elastic/spring/wire breaks

17
Q

State Hooke’s law.

A

Force is proportional to extension

18
Q

Explain how extension of the spring is calculated in the Hooke’s law experiment.

A

Extension = length - original length
(Ext = l - lo)

19
Q

On cars/cyclists, instead of:
Weight - downwards
OR
Upthrust - upwards
It is…

A

Traction - left or right

20
Q

Where the line is just straight, and does not go any higher on velocity time graphs, it is..

A

The terminal velocity

21
Q

If a block’s initial velocity (u) is 10 m/s to the left, and then 500N of force to the right is applied to it, what would happen?

A

It would decelerate

22
Q

If a 18kg block’s initial velocity (u) is 10 m/s to the left, and then 500N of force to the right is applied to it, calculate the acceleration of the block.

A

F = ma
A = F/m
500N/18kg = -27.8 m/s^2
(It’s negative because it’s going to the left and decelerating )

23
Q

State the equation that links acceleration, final velocity, initial velocity and time.

A

A = (v-u)/t

24
Q

If a block’s initial velocity (u) is 10 m/s to the left, and then 500N of force to the right is applied to it, calculate the final velocity of the block after 30 seconds.
(The block’s acceleration is 27.8m/s^2)

A

A = (v-u)/t
V = at+u
(27.8 x 30)-10m/s
= 824m/s

(Ps I’m not sure about this I thought it was -844 but idk)

25
Q

Name all the vector quantities

A

Force
Displacement
Acceleration
Velocity

26
Q

Name all the scalar quantities

A

Time
Temperature
Speed
Distance
Energy
Mass
(Basically everything except:
Force
Displacement
Acceleration
Velocity)

27
Q

Which is the odd one out? Why?
Displacement
Force
Speed
Acceleration

A

Speed because it is scalar

28
Q

Which one is the odd one out? Why?
Distance
Energy
Velocity
Time

A

Velocity because it is vector

29
Q

If the mass of the vehicle increases, the thinking distance…

A

Does not change

30
Q

If the mass of the vehicle increases, the braking distance…

A

Increases

31
Q

If the speed of the vehicle decreases, the thinking distance…

A

Decreases

32
Q

If the speed of the vehicle decreases, the braking distance…

A

Decreases

33
Q

If there are icy roads, the thinking distance…

A

Stays the same

34
Q

If there are icy roads, the braking distance…

A

Increases