Dynamics Flashcards
Which quantity can be completely described by its magnitude and direction?
A vector quantity can be completely described by its magnitude and direction.
What are three ways to reduce friction?
Three ways to reduce friction are lubrication, smooth surfaces, streamlining…
What is the energy change when a ball is thrown up in the air?
When a ball is thrown up in the air, the energy change is
kinetic energy to potential energy.
What is Newton’s 1st Law?
If the forces on an object are balanced, then the object will either
- stay at rest
- move with a constant velocity in a straight line
For projectile motion, what is the only equation you should use for the vertical part of the motion?
For the vertical part of the motion, the only equation which should be used is
For projectile motion, what is the only equation you should use for the horizontal part of the motion?
For the horizontal part of the motion, the only equation which should be used is
Name the three quantities shown in this formula.
EW = work done
F = unbalanced force
d = distance
What is a projectile?
A projectile is an object which is moving only under the influence of gravity.
(assume that air resistance is negligible)
What is the definition of a vector quantity?
A vector quantity has both
magnitude and direction.
Give 5 examples of scalar quantities.
Speed, distance, mass, time, energy.
Name the three quantities shown in this formula.
s = displacement
v = velocity
t = time
What three things can a force change?
A force can change an object’s shape, speed or direction.
What does the prefix G stand for?
G stands for giga
giga = x 109
Which quantity is represented by the symbol v , in the equation shown?
v = velocity
Use Newton’s 3rd Law to explain how a rocket accelerates.
Newton’s 3rd Law is about action and reaction forces.
In a rocket, the rocket pushes the gases downwards, and the gases push up against the rocket (causing it to accelerate).
What is meant by the statement,
“An object has an acceleration of 5 ms-2” ?
This means the object’s velocity is increasing by 5 ms-1 every second.
What is the energy change when a ball is dropped?
When a ball is dropped, the energy change is
potential energy to kinetic energy.
What is the unit for work done?
The unit for work done is joules (J).
(work done is an amount of energy transferred)
For projectile motion, why is this the only equation you should use for the horizontal part of the motion?
For the horizontal part of the motion, the velocity is constant.
What is the unit for speed?
The unit for speed is metres per second
(ms-1)
What is meant by terminal velocity?
When a falling object (e.g. a skydiver) accelerates, the air resistance acting against the object increases, until it is balanced with the object’s weight. When the forces are balanced, it will travel at a constant speed (called ‘terminal velocity’).
What does the prefix M stand for?
M stands for mega
mega = x 106
Name the three quantities shown in this formula.
F = unbalanced force
m = mass
a = acceleration
What is the energy change when a car applies its brakes?
When a car applies its brakes, the energy change is
kinetic energy to heat energy.
What is the definition of a scalar quantity?
A scalar quantity has magnitude only.
What does the prefix µ stand for?
µ stands for micro
micro = x 10-6
What is Newton’s 3rd Law?
Newton’s 3rd Law states that for every ‘action’ force there is an equal but opposite ‘reaction’ force.
What is the unit for time?
The unit for time is seconds (s)
What is the unit for velocity?
The unit for velocity is metres per second (ms-1)
What does the prefix n stand for?
n stands for nano
nano = x 10-9
What is meant by balanced forces?
Balanced forces means forces which are the same size but in opposite directions.
What is the difference between mass and weight?
Mass is a measure of the amount of ‘stuff’ that makes up an object.
Weight is the force due to gravity acting on an object.
What is the unit for displacement?
The unit for displacement is metres (m)
What does the prefix k stand for?
k stands for kilo
kilo = x 103
Which quantity is represented by the symbol Ep?
Ep = potential energy
Is the mass of an object constant at all points in the universe?
Yes. The mass of an object does not change, regardless of the force of gravity.
1kg on Earth would be 1kg on the Moon, 1kg in outer space, and so on.
What is the unit for mass?
The unit for mass is
kilograms (kg)
What is Newton’s 2nd Law?
If the forces on an object are unbalanced, the object will accelerate in the direction of the unbalanced force.
F = m x a
What does the prefix m stand for?
m stands for milli
milli = x 10-3
Give 5 examples of vector quantities.
Velocity, displacement, weight, force, acceleration.
If the forces acting on the balloon are balanced, describe the motion of the balloon.
(there are two possible answers!)
If the forces acting on the balloon are balanced, the balloon will
* stay at rest
OR
* move at a constant speed in a straight line
By referring to the horizontal and vertical parts of its motion, explain the curved path of a projectile.
A projectile has
constant horizontal velocity and
constant vertical acceleration.
What is meant by acceleration?
Acceleration is the change in velocity per second.
For projectile motion, why is this the only equation you should use for the vertical part of the motion?
For the vertical part of the motion, the acceleration is constant (it’s not a constant velocity).
What is the unit for weight?
The unit for weight is newtons (N)
Name the forces acting on a hot-air balloon, accelerating upwards.
The balloon would have weight acting downwards and upthrust (or buoyancy) acting upwards.
Which quantity is represented by the symbol g?
g = gravitational field strength
Which quantity is represented by the symbol Ek?
Ek = kinetic energy
What is friction?
Friction is a force which opposes an object’s motion. Friction occurs when two surfaces come in contact with each other.
Name the three quantities shown in this formula.
d = distance
v = speed
t = time
Is the weight of an object constant at all points in the universe?
No - the weight of an object depends on its mass and the gravitational field strength. Therefore, the weight of an object can vary at different points in the universe.
What is the unit for distance?
The unit for distance is metres (m)
How would you calculate distance from a velocity-time graph?
Distance = area under a velocity-time graph
What is the unit for acceleration?
The unit for acceleration is metres per second squared
(ms-2)
Name the four quantities shown in this formula.
a = acceleration
v = final velocity
u = initial velocity
t = time
What is the unit for force?
The unit for force is newtons (N)
What is the unit for energy?
The unit for energy is joules (J)
Which quantity can be completely described by its magnitude only ?
A scalar quantity can be completely described by its magnitude only.
What is the unit of mass?
The unit of mass is kilograms.
Please note - this is the ONLY standard unit that has “kilo” - it should NOT be converted into grams!
