Mechanics Flashcards

1
Q

Define scalar quantities

A

Has magnitude only.

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

Define vector quantities

A

Has magnitude and direction.

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

What are some examples of scalar quantities?

A
temperature
mass
distance
energy
speed
density
time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some examples of vector quantities?

A
velocity
displacement
acceleration
force
weight
momentum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How can you calculate the resultant vector?

A

pythagoras

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How can you calculate the final vector?

A

trigonometry

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

What is instantaneous velocity?

A

Velocity at a given point

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

Define speed

A

How fast something is moving (regardless of direction).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define displacement

A

How far an object has travelled from its starting point in a given direction.

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

Define velocity

A

The rate of change of an object’s displacement.

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

Define acceleration

A

The rate of change of an object’s velocity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is meant by uniform?

A

Constant - e.g. uniform acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define weight

A

The force on an object due to gravity.

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

What is meant by free fall?

A

When the only force acting on the object is its weight, so it accelerates towards the ground.

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

What shape does a displacement-time graph have?

A

Accelerating object: always be a curve.
Uniform acceleration: gradient is constant
Constant velocity: straight

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

How do you find instantaneous velocity on a displacement-time graph?

A

Draw a tangent to the curve to a certain point and find its gradient.

17
Q

What does a v-t graph represent?

A

Acceleration

  • straight line = uniform acceleration
  • steeper gradient = greater acceleration
18
Q

What does the area under a v-t graph show?

A

Displacement of an object.

19
Q

What does a a-t graph show?

A

How an object’s acceleration changes over time.

20
Q

What are the features of a a-t graph?

A

height = object’s acceleration at that time
area under graph = object’s change in velocity
if a is 0 = constant velocity

21
Q

What is Newton’s first law?

A

An object at rest stays at rest and an object in motion stay in motion unless acted upon by unbalanced forces.

22
Q

What is Newton’s second law?

A

Acceleration is directly proportional to the magnitude of the net force and inversely proportional to the mass of the object. F = ma

23
Q

What is Newton’s third law?

A

For every action, there is an equal and opposite reaction.

24
Q

State the properties of pairs of forces in an interaction between bodies

A
  • act in opposite directions
  • equal magnitude
  • same type of force
  • act on same bodies
25
What is the principle of conservation of linear momentum?
Momentum is always conserved (when no external forces act).
26
Define the 'moment of a force'
The turning effect of a force
27
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred to one store or another.
28
What are the two main types of friction?
Friction between: - solids - fluids (drag/air resistance)
29
What is terminal velocity?
When the friction force equals the driving force.
30
How does weight and air resistance act on a skydiver?
- leaves plane: accelerates (freefall) - air resistance = weight (terminal velocity) - after parachute: air resistance increases (bigger than their weight) - slows down until new terminal velocity reached again