Additional Physics 40 flashcards Jack Young's

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1
Q

What will happen if the resultant force acting on a stationary object is zero?

A

The object will stay stationary.

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2
Q

What is the unit of mass?

A

Kg

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3
Q

How are force, mass and acceleration linked?

A

force=mass*acceleration

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4
Q

Unit for force?

A

Newtons (N)

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5
Q

Unit for acceleration?

A

metres per second squared

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6
Q

Velocity units?

A

Metres per second (m/s)

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7
Q

what does a horizontal line on a distance on a distance-time graph represent?

A

the object is stationary.

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8
Q

what is the different between speed and velocity?

A

the velocity of an object is its speed in a given direction.

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9
Q

what does the gradient of a velocity-time graph represent?

A

acceleration.

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10
Q

What are the units for acceleration?

A

Metres per second squared

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11
Q

what does a horizontal line on a velocity-time graph represent?

A

the object is moving at a constant velocity.

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12
Q

how do you calculate the acceleration from a velocity-time graph?

A

use a = (v-u)/t where a=acceleration (m/s^2), v=final velocity (m/s), u=initial velocity (m/s) and t=time (s).

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13
Q

what happens to the forces when a vehicle travels at a steady speed?

A

the resistive forces balance the driving force.

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14
Q

which force are most of the resistive forces acting on a vehicle caused by?

A

air resistance.

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15
Q

how is the breaking force affected by speed?

A

the bigger the speed the greater the breaking force required to stop it in a certain distance.

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16
Q

what is ‘stopping distance’?

A

the distance the driver travels during the drivers reaction time (thinking distance), and the distance it travels under the breaking force (breaking distance)

17
Q

what three things can a drivers reaction time be affected by?

A

tiredness, drugs and alcohol.

18
Q

what happens to the temperature of the breaks when you apply them and why?

A

it increases because the work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle so the temperature of the brakes increase.

19
Q

what can braking distance be affected by?

A

poor weather (icy and wet conditions) and poor conditions of the vehicle (tyres and breaks).

20
Q

if an object moves through the fluid faster, what happens to the frictional force?

A

it will increase.

21
Q

what does a falling object initially accelerate?

A

due to the force of gravity.

22
Q

what will eventually happen to the resultant force of a falling object?

A

it will be zero.

23
Q

what is ‘terminal velocity’?

A

the speed an object reaches when the resultant forces are zero, measured in m/s.

24
Q

how do you calculate the weight of an object?

A

mass (kg) x gravity (N/kg) = Weight (N).

25
Q

what is ‘work done’?

A

when a force causes an object to move through a distance. W= F (N) x d (m).

26
Q

what is the unit for work done?

A

joules (J).

27
Q

what is transferred when work is done on an object?

A

energy.

28
Q

will the amount of work done to move an object across ice be smaller or greater than to move the same object the same distance across grass?

A

it will be smaller because there are less frictional forces to counteract.

29
Q

what is power and what are its units?

A

the work done or energy transferred in a given time P= E/t. The units are watts (w), energy are joules (J) and time in seconds (s).

30
Q

what are the units for gravitational field strength (g)?

A

N/kg.

31
Q

if the gravitational field strength on earth is 10 N/kg what is the weight of someone who has a mass of 70kg?

A

70kg X 10 N/kg=700 N (Weight = m x g).

32
Q

how are forces represented?

A

by an arrow, ideally from where the force originates.

33
Q

what is a resultant force?

A

when a single force replaces all of the existing forces, the resultant force has the same motion as all of the forces added together.

34
Q

what will happen of the resultant force acting on a stationary object is not zero?

A

the object will accelerate in the direction of the resultant force.

35
Q

what does the gradient of a distance-time graph represent?

A

constant speed (velocity).

36
Q

how do you calculate the speed (velocity) from a distance-time graph?

A

speed (velocity) is a distance/time so use the axis to find the distance. travelled and divide it by the time taken.