Mechanics Flashcards
(96 cards)
1
Q
What is the definition of distance?
A
It is the intervals between two points.
2
Q
What is displacement?
A
It is the shortest distance between two points.
3
Q
What is scalar?
A
Scalar is a (physical) quantity which only has magnitude. This means it only has a positive value.
4
Q
What is a vector?
A
Vector is a (physical) quantity that has magnitude and direction. This means it can be positive or negative value.
5
Q
Give 4 examples of scalar quantities?
A
Speed
Mass
Energy
Distance
6
Q
Give 4 examples of vector quantities?
A
Velocity
Acceleration
Momentum
Displacement
7
Q
- What is scalar X Vector?
- What is Scalar X Scalar?
- What is Vector X Vector?
- What is the square of a vector?
- What is the square of a scalar?
A
- Vector
- Scalar
- Scalar
- Scalar
- Scalar
8
Q
What is energy?
A
The ability to do work.
9
Q
What is dissipated energy?
A
Energy that’s wasted.
10
Q
What is the two conditions in which work is done?
A
-When there is a force applied
-When a force is able to move an object through a distance
11
Q
What is potential energy?
A
Energy that an object possesses by a virtue of its position (its state of being).
12
Q
What is an equilibrant?
A
Force capable of balancing another force and producing an equilibrium.
13
Q
What is a physical quantity?
A
A quantity that can be defined or measured.
14
Q
What are the two types of physical quantities?
A
-Fundamental/Base quantities
-Derived quantities
15
Q
What is a base quantity?
A
Quantities on which other quantities depend on SI units. All units in Physics can be reduced to 6 base units.
16
Q
What is the only system of measurement that is officially used in almost every country around the world?
A
Base units
17
Q
What are the 6 base units?
A
-Mass
-Length/Distance
-Time
-Current
-Temperature
-Amount of a substance
18
Q
What is the SI base units and symbols for temperature and amount of a substance?
A
Temperature-Kelvin-K
Amount of a substance-Mole-mol
19
Q
What are derived quantities?
A
They are formed from a combination of two or more base quantities. (e.g. Speed= Distance/Time)
20
Q
What are derived units?
A
They are formed from a combination of base units
21
Q
What is Newtons first Law called?
A
Law of inertia
22
Q
What is Newtons first Law?
A
If the sum of the forces acting on a body is 0, the body will be at rest if it was already at rest, or keep moving with a constant velocity if it was already moving.
23
Q
What is Newtons second Law?
A
The acceleration of an object is directly proportional to its mass. The direction of acceleration is the direction of net force.
24
Q
What is Newtons third Law called?
A
Action-Reaction Law.
25
What is Newtons third Law?
For every force acting on a body, there is an equal and opposite force.
26
What is inertial mass?
A measure of how much a body resists change in its velocity.
27
What is instantaneous velocity?
Velocity at a specific moment in time
28
What are the three types of graphs that are used to represent motion?
- Displacement time graphs
- Velocity time graphs
- Acceleration time graphs
29
What is the formula for velocity?
change in acceleration/change in time
30
What is the formula for uniform (constant) acceleration?
-(final velocity- initial velocity)/time
-(v-u)/t
31
What are kinematic equations of motion?
They are the set of four equations which can describe any object moving with constant acceleration. (SUVAT equations)
32
What are the four SUVAT equations?
v= u+at
s= (u+v)t/2
s= ut+0.5at²
v²= u²+2as
33
Go over projectile motions graph
34
In a displacement time graph, what does:
-the gradient (slope) show
-Area under a curve
-The slope shows the velocity. If it is a negative slope, it is a negative velocity. If it is a positive slope, it is a positive velocity and if there is zero slope, the object is at rest.
-The area under a curve is meaningless
35
In a velocity time graph, what does:
-the gradient (slope) show
-Area under a curve
- The slope shows acceleration. A straight slope shows uniform acceleration. A curved slope shows non-uniform acceleration. A positive slope shows positive acceleration and a negative slope shows deceleration. A zero slope shows constant acceleration.
- Area under curve shows distance travelled.
36
In an acceleration time graph, what does:
-the gradient (slope) show
-Area under a curve
-A zero slope shows constant acceleration. A positive slope shows an increase in acceleration. A negative slope shows a deceleration.
- Area under curve shows change in velocity.
37
What is velocity?
The rate of change of displacement.
38
What are the 4 types of velocity?
- Uniform velocity
-Non-uniform velocity
-Average velocity
-Instantaneous velocity
39
What is the formula for velocity?
Velocity= Distance/Time
-This can also be used for instantaneous and average velocity
40
What do the symbols of SUVAT represent?
s= displacement
u= initial velocity
v= final velocity
a= acceleration
t= time interval
41
When are SUVAT only used?
When acceleration is constant but not 0.
42
What is the numerical value of gravity in physics?
9.81
43
What do objects in freefall have a constant velocity of and why?
9.81 because the acceleration is gravity.
44
When an object is slowing down what is the value of acceleration?
Negative value
45
What is the velocity of an object when it is at its peak?
0
46
What is a projectile?
A particle moving freely (non-powered) under gravity in a two dimensional plane at an angle to the horizontal line from where it starts from.
47
STATEMENT:
The motion of an object undergoing projectile motion consists of a vertical component and horizontal component which need to be evaluated separately.
48
What is the formula for finding the vertical height of a projectile?
u (as in SUVAT)= u (as in gradient of initial velocity) X sinθ
49
What is the formula for finding the horizontal height of a component?
u (as in SUVAT)= u (as in gradient of initial velocity) X cosθ
50
What are the three key terms in projectile motion and what do they mean?
- Time of flight= How long a projectile is in the air for.
-Maximum height= Height at which the object is momentarily at rest.
-Range= Horizontal distance travelled by object
51
Can you use SUVAT in projectile motion?
Yes
52
What is the formula for time taken to reach maximum height?
usinθ/g (u is the gradient of initial velocity)
53
What is the formula to find out maximum height?
(usinθ)²/2g (u is the gradient of initial velocity)
54
What is the formula for time of flight?
2usinθ/g
55
What are free body diagrams useful for?
Modelling forces that are acting on an object.
56
What type of arrows forces represented by?
Vector arrows
57
What does these featured of a vector arrow represent?
-Size
-Arrowhead
-Label
- Size= magnitude of the force
- Arrowhead= direction the force acts
- Label= name or symbol of the force
58
When an object is on a surface, what is the force acting upwards that counter-acts the weight?
Normal reaction force
59
At what angle does the normal reaction force act from the surface?
90 degrees
60
in a free body diagram, if you are given some forces acting on an object, how do you find out the desired force (x)?
1. Draw all the forces on the free body diagram.
2. Remove the object and put all the forces coming from a single point.
3. Re-arrange the forces into a triangle. Make sure to leave the size and direction of the arrows the same.
4. Use Pythagoras or trigonometry to find out the desired force (x).
61
GO OVER FREE BODY DIAGRAM QUESTIONS
62
What is the formula for force?
What are the units for the quantities in the equation?
Force (N) = Mass (g) X Acceleration (s^-2)
63
What is terminal velocity?
When maximum velocity is reached due to drag forces becoming equal with driving force.
64
LOOK AT BOOK FOR SYMETRICAL AND NON-SYMETRICAL EQUILIBRIUM
65
What is moment?
Moment is when a force acts about a fixed point and has a turning effect. Units in Newton metres (Nm).
66
What is the formula for moments?
M=Fs
Moment= Force X Distance (Perpendicular)
67
How can you solve moment in a triangle when θ is not 90 degrees?
M = Fs sin(θ)
Moment = Force X Perpendicular distance X sin(θ)
68
For a system in equilibriujm a clockwise moment is equal to what?
A clockwise moment is equal to an anti-clockwise moment.
69
When finding out moments, what must the distance be?
The distance must be perpendicular to force when finding out moments
70
What is the SI units for moments?
Newton meters (Nm)
71
What is work?
Amount of energy transferred when a force causes an object to move over a certain distance.
72
-What is the formula for work done?
-When can the formula of displacement be used?
-W=Fs Work done (Nm) = Force X Displacement
-The work done equation is used when displacement is parallel.
73
- What happens when the force acts in the direction the object is moving?
- What happens when the force acts in the opposite direction the object is moving?
- when the force acts in the direction the object is moving, the object will gain energy.
- when the force acts in the opposite direction the object is moving, the object will lose energy.
74
What is kinetic energy?
Energy an object has due to its motion.
75
What is the formula for kinetic energy?
Ek= 1/2 X mv²
Ek=Kinetic energy m=mass v=velocity
76
What is tensile strain?
Change in length per unit (from original length).
77
What is gravitational potential energy (Ep or GPE)?
Energy that a mass of an object has due to its position in a gravitational field.
78
What happens to GPE when
-A mass is lifted?
-A mass falls?
-When a mass is lifted, it gains GPE
-When a mass is falling, it loses GPE
79
What is the formula for GPE?
GPE= mgh
m= mass g=gravity h=height
80
What is the gravitational field strength at ground level? and why?
GPE=0 as height is 0.
81
What is gravity estimated at?
9.82N
82
Because energy is conserved, in falling objects, the __________ energy is equal to the ___________ energy at the end.
Because energy is conserved, in falling objects, the gravitational potential energy at the start is equal to the kinetic energy at the end.
83
-What is the area under force distance graph show?
- How do you find are under distance-time graph?
- Energy and work done
-E=1/2 X kx²
E=Energy or work done k= gradient x=difference in x axis
84
What is the principle fo conservation of energy?
Energy can't be created or destroyed only transferred from one state to another.
85
What is power?
Power is the rate at which energy is transferred. (Measured in Watts).
86
What is the formulas for power?
P= E/T = W/T
E=Energy T=Time W=Work done
87
What is the formula for efficiency?
Efficiency= Useful energy output/ Total energy output X 100%
88
What are the formulas for acceleration?
Acceleration= (final velocity-inital velocity)/time A=(v-u)/t
Acceleration= Force/Mass A=F/M
89
What is the formula that links gravitational field and force?
g= F/m
gravity= Force/mass
90
What is the definition of momentum?
Momentum is the product of an object's mass and velocity.
91
What is the formula for momentum?
p=mv
momentum= mass X velocity
92
What is the principle of conservation of momentum?
The principle of conservation of momentum is that in a closed system, the total momentum before collision is equal to the total momentum after collision.
93
What is another formula for momentum?
p=Ft
Momentum= Force X Time
94
What is the formula for change in momentum?
m1 u1+m2 u2 = m1 v1+ m2 v2
m=momentum, u=initial velocty, v-final velocity
(NOTE: when objects move in opposite directions, velocity becomes minus so you subtract.
95
- When is the centre of mass and gravity the same?
- When is the centre of mass and velocity not the same?
- Centre of mass and velocity are the same in a small body (Uniform gravitational field).
- Centre of mass and velocity aren't the same in a large body (Non- uniform gravitational field).
96
- When is high stability achieved?
- When is unstable equilibrium achieved?
- When is neutral equilibrium achieved?
- High stability is acheived when the centreo of mass is low down near the base.
- Unstable equilibrium is when an object tips over easily.
- Netral equlibrium is when an object rolls but doesn't tip over.
