mechanics Flashcards

1
Q

what is meant by terminal velocity

A

when the forces acting on the falling object become balanced, the acceleration becomes zero and the object is moving at maximum velocity

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

what is meant by friction

A

a resistance to motion between
an object and a surface or
an object moving through a fluid.
Friction is a force that acts in the opposite direction to the movement

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

what is Newton’s 3rd law?

A

for each force experienced by an object, the object exerts an equal and opposite force

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

what is Newton’s 2nd law?

A

F=ma
the resultant force is directly proportional to the rate of change of momentum and acts in the same direction

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

What is Newton’s first law?

A

an object will remain in its current state of motion, unless acted on by a resultant force.
An object requires a resultant force to be able to accelerate

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

what is the equation for momentum?

A

momentum = mass x velocity
p=mv

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

as well as impulse, what can also be described as the change of momentum?

A

force x time

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

what is impulse?

A

the change in momentum

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

what are the units for impulse and momentum?

A

Ns and Kgm/s

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

what does the area underneath a force-time graph represent?

A

impulse/change in momentum

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

what is the rate of work done equal to?

A

power

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

what is efficiency?

A

useful output/
total output

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

what is meant by the principle of conservation of energy?

A

energy cannot be created or destroyed,
only transferred into other forms of energy
therefore, total energy in a closed system will always remain the same

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

what is the difference between mass and weight?

A

mass is scalar and is not dependent on the gravity acting upon it
weight is a vector and depends on the gravitational field strength

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

what is the principle of moments?

A

for an object in equilibrium,
the sum of clockwise moments (about a pivot) is equal to the sum of anti clockwise moments

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

what does it mean for an object to be in equilibrium?

A

it is not accelerating
it is either stationary or moving at a constant velocity

17
Q

what is a moment and what is its equation?

A

a turning force:
force x perpendicular distance from the point to the line of action of the force

18
Q

what is meant by a couple?

A

a pair of equal and opposite coplanar forces

19
Q

what is meant by centre of mass?

A

the point through which all the mass of an object acts, for a uniform object the centre of mass is the centre of the object

20
Q

what is the change in displacement per unit of time?

21
Q

what is free fall?

A

where an object experiences an acceleration of g

22
Q

what is lift?

A

an upward force which acts on an objects travelling in a fluid

23
Q

what causes lift?

A

an object creating a change in the direction of fluid flow, and it acts perpendicular to the direction of fluid flow

24
Q

What are the properties of a vector quantity?

A

A vector quantity is one that has both a magnitude and a direction.
Examples include velocity, displacement and acceleration.

25
what is an inelastic collision?
A collision in which the total kinetic energy of the system before the collision is not equal to the kinetic energy of the system after the collision.
26
How do you find velocity on a displacement-time graph?
velocity is found by measuring the gradient of a tangent to a displacement-time graph
27
what is the difference between mass and weight?
mass is scalar and is not dependant on the gravity acting upon it weight is a vector and depends on the gravitational field strength W=mg
28
What does it mean for an object to be in equilibrium?
not accelerating, so either stationary or moving at a constant velocity
29
what is a couple?
a pair of equal and opposite coplanar forces
30
where is the centre of mass for a uniform object?
the centre of the object
31
what is the area under a velocity-time graph?
displacement travelled
32
what is the area under an acceleration-time graph?
velocity
33
as speed increases, air resistance ...
increases (proportional to the square of the speed)
34
What is the vertical acceleration in projectile motion?
gravitational field strength, g
35
what happens at terminal velocity?
the forces acting on the falling object become balanced so the acceleration becomes zero the object is moving at maximum velocity
36
Is linear momentum conserved only in elastic collisions?
no, linear momentum is always conserved
37
what can be described as the rate of change of momentum?
force
38
what are two equations for impulse?
I = FΔt = Δmv