Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > Forces > Flashcards

Forces Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Acceleration

A

The rate of change of velocity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Average Speed

A

Distance over time for the entire region of interest.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Braking Distance

A
  • The distance travelled between the brakes being applied and the vehicle coming to a stop
  • It is affected by the vehicle and road conditions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Free-Fall

A

the only force acting on the object is the
force of gravity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Projectile Motion

A
  • The motion of an object that is fired from a point and then upon which only gravity acts is called projectile motion.
  • When solving projectile motion problems, it is useful to split the motion into horizontal and vertical components.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Instantaneous Speed

A

The exact speed of an object at a specific given point.
(Draw tangent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Reaction Time

A

The time taken to process a stimulus and trigger a response to it.
It is affected by alcohol, drugs and tiredness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Thinking Distance

A
  • The distance travelled in the time it takes for the driver to react.
  • It is affected by alcohol, drugs and tiredness.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Velocity

A

The rate of change of displacement.
It is a vector quantity and so has both a direction and a magnitude.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Archimedes’ Principle

A

The upwards force acting on an object submerged in a fluid, is equal to the weight of the fluid it displaces.
(Upthrust = 𝜌liquid 𝑉object 𝑔)
(upthrust = (h2 - h1)𝜌gA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Centre of Gravity/mass

A
  • The single point through which the object’s weight/mass can be said to act.
  • An object will fall if the centre of gravity has moved past it’s pivot (as the direction of moment has changed)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Couple

A
  • A couple consists of a pair of equal and opposite coplanar forces that act to produce rotation only.
  • A couple has the following characteristics:
    • Equal in magnitude
    • Opposite in direction
    • Perpendicular to the distance between them
    • Zero acceleration (resultant force)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Drag

A

The frictional force that an object experiences when moving through a fluid (air).

Factors of drag
- Surface area in contact with fluid
- Density of fluid
- Speed of the object (d∝v2)
- All apply to objects travelling through air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Equilibrium

A

For an object to be equilibrium, both the resultant force and resultant
moment acting on the object must be equal to zero.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Free-Body Diagram

A

A diagram showing all the forces acting on an object.
It is a good starting point to any mechanics problem.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Friction

A

The resistive force produced when there is relative movement between two surfaces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Moment of Force

A

The product of a force and the perpendicular distance from the line of action of the force to the pivot.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Newton’s Second Law

A
  • The sum of the forces acting on an object is equal to the rate of change of momentum of the object.
  • This is also expressed as the net force acting on an object equaling the product of the object’s mass and acceleration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Principle of Moments

A

For an object to be in equilibrium, the sum of the clockwise moments acting about a point must be equal to the sum of the anticlockwise moments acting about the same point.
(It can be spinning)

20
Q

Tension

A

The result of two forces acting on an object in opposite, outwards directions

21
Q

Terminal Velocity

A
  • The terminal velocity of an object occurs when the resistive and driving forces acting on the object are equal to each other.
  • Initially, only the weight (W = mg) acts on the object, causing acceleration.
  • As velocity increases, the drag force increases, reducing the resultant force and acceleration.
  • When the drag force equals the weight, the resultant force becomes zero, and acceleration stops, leading to terminal velocity.
22
Q

Upthrust

A
  • The upwards force that a fluid applies on an object.
  • If floating U=W
  • If moving Fresultant = U - W - D
23
Q

Conservation of Energy

A
  • In a closed system with no external forces, total energy remains constant.
  • Energy can change form within the system.
  • Examples include gravitational potential energy to kinetic energy in a falling object, chemical energy to electrical and light energy in a battery, and elastic potential energy to kinetic energy in a horizontal mass on a spring.
  • There may also be work done against resistive forces such as friction
24
Q

Brittle

A

A brittle object is one that shows very little strain before reaching its breaking stress.
- High YM + no plastic region

25
Q

Elastic Deformation

A
  • If a material deforms with elastic behaviour, it will return to its original shape when the deforming forces are removed.
  • The object will not be permanently deformed.
26
Q

Elastic Potential Energy

A
  • The energy stored in an object when it is stretched is equal to the work done to stretch the object.
  • This energy can be determined from the area under a force-extension graph.
27
Q

Hooke’s Law

A

The extension of an elastic object is directly proportional to the force applied to it up to the object’s limit of proportionality.

28
Q

Plastic Deformation

A
  • It will not return to its original shape when the deforming forces are removed.
  • The object will be permanently deformed.
29
Q

Spring Constant

A
  • The constant of proportionality for the extension of a spring under a force is the spring constant. (Nm-1)
  • The higher the spring constant, the greater the force needed to achieve a given extension.
    (1/K total for springs in series)
30
Q

Strain

A

The ratio of an object’s extension to its original length. It is a ratio of two
lengths and so has no unit.

31
Q

Tensile Deformation

A

The changing of an object’s shape due to tensile forces. (Pulling)
Opposite is compressive deformation

32
Q

Ultimate Tensile Strength

A

The maximum stress than an object can withstand before fracture occurs

33
Q

Young Modulus

A

The ratio of stress to strain for a given material. Its unit is the
Pascal (Pa).

34
Q

Conservation of Momentum

A

The total momentum of a system before an event must be equal to the total momentum of the system after the event, assuming no
external forces act.
(kgms-¹) Or (Ns)

35
Q

Types of Collisions

A
  • An elastic collision is one in which the total kinetic energy of the system before the collision is equal to the total kinetic energy of the system after the collision.
  • A collision is inelastic if kinetic energy is not conserved.
  • Prove by working out KE before and after and compare values
36
Q

Impulse

A
  • The change of momentum of an object when a force acts on it is called impulse.
  • It is equal to the product of the force acting on the object and the length of time over which it acts.
    (Area under a force-time graph)
37
Q

Newton’s First Law

A
  • Object will remain in its current state of motion unless acted on by a resultant force.
  • For an object to accelerate, it requires a resultant force.
38
Q

Newton’s Third Law

A

Every action has an equal and opposite reaction. If an object exerts a force on another object, then the other object must exert a force back, that is opposite in direction and equal in magnitude.

39
Q

Car safety

A
  • In a car collision, airbags and seatbelts increase the time (𝑡) for the driver’s deceleration, reducing the force (𝐹) exerted on the body (𝐹 = (𝑚𝑣 - 𝑚𝑢) / 𝑡).
  • Crumple zones absorb energy by deforming, further reducing the force on the driver.
40
Q

Pivot

A

(choose a pivot when finding a moment. It will also remove the reaction force of pivot)

The point about which an object will
turn when it experiences a moment

Anything can be a pivot

41
Q

Polymeric material

A
  • A material made up of long repeating chains of molecules (rubber)
  • Polymeric materials can endure a lot of tensile stress before breaking
  • There is no plastic deformation
  • The loading curve is different to the unloading curve as some energy is lost as thermal energy during stretching
    (Hysteresis loop)
42
Q

Pressure in a liquid

A
  • An object immersed in a column of fluid experiences pressure due to the weight of the fluid.
  • The pressure at the base of a column of fluid is the same in all directions.

p = mg/A = (ρV)g/A

Volume ÷ cross sectional area = height

  • Sometimes have to add atmospheric pressure
43
Q

Time graph

A
  • The gradient of a displacement-time graph is the velocity
  • The gradient of a velocity-time graph is the acceleration
  • The area under a velocity-time graph is the displacement
  • The area under an acceleration-time graph is the velocity
44
Q

Change in Momentum if it rebounds (hits a wall)

A
  • Change in momentum is only due to horizontal velocities
  • ∆p = m(vf - vi)
45
Q

Torque

A
  • The size of a turning effect
  • τ = Fd

Where:

τ= torque (N m)

F= one of the forces (N)

d= perpendicular distance between the forces (m)

46
Q

Elastic limit

A
  • Won’t return to original length
  • plastic region
47
Q

Ductile

A
  • Drawn to wire
  • Large plastic region

Physics (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions