Physics
0.0 / 5
- Created by: leo1223
- Created on: 09-06-18 20:06
What is a force?
A force is a push or pull that is applied by one object to another
1 of 83
What is force measured in?
Newtons (N)
2 of 83
What are contact forces?
Contacts forces are objects that are physically touching the force i.e. a parachute in contact with air
3 of 83
What are non-contact forces?
Non-contacts are objects that are physically not in contact with the force, but still have the force applied to them
4 of 83
Name 4 contact forces
Friction, air resistance, tension and contact force
5 of 83
Name 3 non-contact forces
Gravity, electrostatic force and magnetic force
6 of 83
What is a scalar quantity?
A scalar quantity has magnitude (size)
7 of 83
What is a vector quantity?
A vector quantity has magnitude and direction
8 of 83
How are vector quantities represented?
Vector quantities can be represented by an arrow, the length of the arrow represents the magnitude, the direction of the arrow shows its direction
9 of 83
Name 5 scalar quantities
Speed, distance, energy, temperature and mass
10 of 83
Name 5 vector quantities
Force, velocity, momentum, acceleration and displacement
11 of 83
What happens (in terms of acceleration) when an object is dropped?
If an object is dropped its speed increases as it falls. It accelerates because it is pulled towards the centre due to gravity
12 of 83
What is the resultant force?
The resultant force is a single force that has the effect as two or more forces acting together
13 of 83
What happens to two forces that act in the same direction?
Two forces that act in the same direction produce a resultant force that is greater than either individual force
14 of 83
What happens to two forces that act in opposing directions?
Two forces that act in opposite directions produce a resultant force that is smaller than either individual force
15 of 83
What is mass?
Mass is the amount of substance that is present in an object. It is measured in kilograms
16 of 83
What is weight?
Weight is the force acting on that mass, if it is in a gravitational field, as weight is a force, it is measured in newtons
17 of 83
Describe how gravity works?
Gravity is a non-contact force, anything in a gravitational field will experience a force of attraction e.g. on earth everything is attracted to earth's core
18 of 83
What is meant by work done?
Work is done when energy is transferred from one store to another. Work is also done when a force causes an object to move. When work is done against frictional forces acting on an object, the object's temperature increases.
19 of 83
What is Newton's first law?
Newton's first law of motion states that an object remains in the same state of motion unless a resultant force acts on it. If the resultant force is zero; a stationary object stays stationary, a moving object continues to move at the same velocity
20 of 83
What may happen to an object when a forcing is acting upon it?
When a force acts on an object, the object may change shape by bending, stretching or compressing, or a combination of all three shape changes
21 of 83
What is a change in shape due to a force called?
Deformation
22 of 83
What are the two different types of deformation?
Elastic deformation is reversed when the force is removed, inelastic deformation is not fully reversed when the force is removed, there is a permanent change in shape
23 of 83
Give two examples of deformation
A rubber band undergoes elastic deformation when stretched a little, A metal drink can undergoes inelastic deformation when it is squashed
24 of 83
What is extension?
Extension happens when an object increases in length
25 of 83
What is compression?
Compression happens when it decreases in length
26 of 83
What is the limit of proportionality?
The limit of proportionality refers to the point beyond which Hooke's law is no true when stretching a material
27 of 83
What is the elastic limit of a material?
The elastic limit of a material is the furthest amount it can be stretched or deformed while being able to return to previous shape. Once a material has gone past its elastic limit, its deformation is said to be inelastic
28 of 83
What is a moment?
A moment is the turning effect of a force. Moments act about a point in a clockwise or anticlockwise direction. The point chosen could be any point on the object, but the pivot (middle) is usually chosen
29 of 83
What happens when an object is balanced?
If an object is balanced, the total clockwise moment about a pivot is equal to the total anticlockwise moment about that pivot
30 of 83
What is inertia?
Inertia is the natural tendency of objects to resist changes in their velocity
31 of 83
What is inertial mass?
Inertial mass is a measure of how difficult it is to change the velocity of an object
32 of 83
What is the equation for inertial mass?
Inertial mass = Force / Acceleration
33 of 83
What is Newton's third law?
Newton's third law states that whenever two objects interact, the forces they exert on each other are equal and opposite
34 of 83
What does a lever consist of?
A pivot, an effort and a load
35 of 83
What is a force multiplier?
A force multiplier is something that increases the effect of a force
36 of 83
What are gears?
Gears are wheels with toothed edges that rotate on an axel or shaft, the teeth of one gear fit into the teeth of another gear, this lets one gear turn another which allows one axel or shaft to turn another shaft
37 of 83
Explain what happens when one gear turns with another gear attached?
As one gear turns, the other must also turn. Where the gears meet, the teeth must both move in the same direction. The gears rotate in opposite directions
38 of 83
If a larger gear is driven by a smaller gear, what happens to the rotation and moment?
If a larger gear is driven by a smaller gear, the large gear will rotate slowly but will have a greater moment
39 of 83
If a smaller gear is driven by a larger gear, what happens to the rotation and moment?
If a smaller gear is driven by a larger gear, the larger gear will rotate quickly but will have a smaller moment
40 of 83
What is momentum?
Momentum is the product of mass and velocity, it is a vector quantity. A moving object has momentum.
41 of 83
What happens to the momentum when a car suddenly stops?
When a car stops suddenly. Its momentum becomes zero. The larger the force applied to the car, the quicker its momentum becomes zero
42 of 83
Why are cars designed to increase the time a car takes to stop?
Safety features are designed to increase the time a car or its passenger takes to stop. The longer the time, the smaller the force on the car's occupants, therefore the passengers are safer the longer the car takes to stop
43 of 83
What are crumple zones?
Crumple zones increase the time between first impact and the car stopping. The rate of change of momentum is smaller, reducing the force on the car's occupants. The crumple zones are the back and the front of the car
44 of 83
What is a closed system?
A closed system is something that is not affected by external forces
45 of 83
What does the conservation of momentum state?
The conservation of momentum states that, in a closed system, the total momentum before a collision is equal to the total momentum after the collision
46 of 83
What is thinking distance?
Thinking distance is the distance travelled during the reaction time. It is the distance travelled between the driver seeing a danger and taking action to avoid it, such as braking
47 of 83
What is braking distance?
Braking distance is the distance travelled before a car stops after the brakes have been applied. It increases as the speed of the car increases
48 of 83
What is the equation for stopping distance?
Stopping distance = thinking distance + braking distance
49 of 83
What factors affect reaction time and therefore affect the thinking distance?
Reaction time and hence thinking distance may increase if a driver is: tired, under the influence of alcohol or other drugs, distracted or lacks concentration
50 of 83
What factors cause the braking distance to increase?
The braking distance may increase when: the road is wet or icy, the car has poor brakes or bald tyres, the speed of the car is great
51 of 83
What is the average reaction time for humans?
Reaction time varies between 0.2s and 0.9s, but is typically about 0.7s
52 of 83
Describe what happens when a vehicle begins to decelerate?
Kinetic energy is transferred away form a vehicle that is slowing down. Work done by the friction force between the brakes and rotating wheel reduces the kinetic energy of the vehicle. Energy is transferred to the brake pads, which heat up
53 of 83
What happens when a car decelerates rapidly?
If deceleration is very rapid, it means a large braking force is being applied. This can result in the brake pads overheating causing the driver to lose control of the direction of the vehicle
54 of 83
Why is it dangerous when a car decelerates rapidly?
When a car decelerates rapidly, this can be dangerous for the occupants. A large deceleration means the momentum of passengers is reduced very quickly. A rapid change in momentum can cause injury due to the large force entered on the person.
55 of 83
What are the purpose of seat belts and air bags?
The purpose of seat belts and air bags is to bring the passenger to rest over a longer time period than that taken by the car
56 of 83
What is the centre of mass?
The weight of the object can be considered to act at a single point referred to as the object's centre of mass
57 of 83
What happens when an objects vertical line through its centre of mass falls outside its base?
An object becomes unstable when the vertical line through its centre of mass falls outside its base, which acts as a pivot. The weight of the object causes a turning effect about this pivot
58 of 83
What do levers do?
Levers enable us to move a large force using a small one but the distance moved is much smaller
59 of 83
What are gears used for?
Gears are used for transmitting the rotational effect of a force from part of a machine to another
60 of 83
How does pressure act in fluids?
The pressure in a fluid acts in all direction
61 of 83
What is a fluid?
A fluid is either a gas or liquid
62 of 83
What is the correlation between the depth of the water and the pressure?
The deeper you go in water, the greater the pressure becomes.
63 of 83
Why is the pressure greater in deeper waters?
The deeper you are, the greater the weight of the water above you
64 of 83
Is the pressure greater or less on an an object submerged on the bottom surface compared to the top?
A submerged object experiences a greater pressure on the bottom surface than on the top surface. This creates a resultant force upwards. This force is called upthrust
65 of 83
What determines whether a solid object will sink or float in a liquid?
When solid objects are placed in a liquid they will float or sink depending of the solid material compared with the density of the liquid
66 of 83
If a object is denser than a liquid what will happen to the object when it is placed in the liquid?
If the object is denser than the liquid it will sink because the weight is greater than the upthrust
67 of 83
If a object is less dense than a liquid what will happen to the object when it is placed in the liquid?
If the object is less dense than the liquid it will float to the surface as the upthrust is greater than the object's weight
68 of 83
If a object has the exact same density as a liquid what will happen to the object when it is placed in the liquid?
When the object has exactly the same density as the liquid it will stay still, neither sinking nor floating upwards, the weight is equal to the upthrust
69 of 83
What is the key features of the earths atmosphere?
The earths atmosphere is thin compared to the size of earth. It becomes less dense as the altitude increases, less pressure as altitude increases
70 of 83
What causes atmospheric pressure?
Air molecules colliding with a surface cause atmospheric pressure
71 of 83
What is the atmospheric pressure at sea level and the cruising altitude of a plane?
Atmospheric pressure at sea level is about 101,000 Pa compared to the 27,000 Pa at the cruising altitude of a passenger plane
72 of 83
Why does atmospheric pressure decrease as the altitude increases?
Atmospheric pressure decreases as the height of a surface above ground level increases. This is because as the altitude increases: the number of air molecules decrease, the weight of the air decreases, there is less air above a surface
73 of 83
Why must an aircraft be pressurised while flying at high altitudes?
An aircraft must be pressurised at high altitudes as if the air pressure is too low, humans will not be able to take in oxygen quickly enough to meet their bodies needs
74 of 83
What is velocity of an object?
The velocity of an object is its speed in a particular direction
75 of 83
What acceleration will any object have as it free falls near the surface of the earth?
9.8 metres per second
76 of 83
What is meant by terminal velocity?
At seminal velocity, the object moves at a steady speed in constant direction because the resultant force acting on it is zero
77 of 83
When can terminal velocity be reached?
Only objects falling through fluid eventually reach terminal velocity
78 of 83
Describe the three stages that take place as an object falls through a fluid?
At the start, a object accelerates downwards due to the force of gravity, as the object's speed increases, frictional forces like air resistance increase, at terminal velocity, the weight of the object due to gravity is balanced by frictional forces
79 of 83
What is meant by uniform motion?
Uniform motion is an object moving at a constant velocity
80 of 83
What is known about objects that are moving in uniform motion?
Objects that move in uniform motion must have two or more forces acting on that object in opposing directions, which are cancelled out causing the resultant force to be zero, and the object to stay at constant velocity in the same direction
81 of 83
What is meant by non-uniform motion?
Non-Uniform motion is when an object is moving a changing velocity e.g. accelerating or decelerating
82 of 83
What is known about object that are moving in non-moving motion?
Objects that move in non-uniform have at least 1 force acting on upon that object, which causes the resultant force is not 0, if two forces are acting upon the object in opposing direction, one force must be greater than the other
83 of 83
Other cards in this set
Card 2
Front
What is force measured in?
Back
Newtons (N)
Card 3
Front
What are contact forces?
Back
Card 4
Front
What are non-contact forces?
Back
Card 5
Front
Name 4 contact forces
Back
Related discussions on The Student Room
Similar Physics resources:
1.0 / 5 based on 2 ratings
1.0 / 5 based on 2 ratings
0.0 / 5
1.0 / 5 based on 2 ratings
1.0 / 5 based on 8 ratings
1.0 / 5 based on 1 rating
0.0 / 5
1.5 / 5 based on 8 ratings
1.0 / 5 based on 2 ratings
Comments
No comments have yet been made