Force and Motion Flashcards
What does a horizontal line represent on a graph of displacement against time?
A stationary object
What does a line with a constant gradient represent on a graph of displacement against time?
An object with constant velocity
What does a curved line represent on a graph of displacement against time?
Acceleration or deceleration
What does a horizontal line represent on a graph of displacement against time
An object with a constant velocity
What does a line with a constant gradient represent on a graph of displacement against time?
The constant acceleration of the object for a positive gradient or constant deceleration for negative gradient
What does the area under a velocity-time and acceleration-time graph represent?
The displacement of the object and the change in velocity respectively
Describe how the terminal velocity of an object can be determined using light gates?
- light gates are connected to a timer or data logger
- the time when each of the two beams are broken by the object and the time difference (with a number of repeats done to improve accuracy) combined with the known distance between the light gates are used to find the velocity
- velocity = distance / time
Meaning of scalar quantity
Only magnitude but not direction
Meaning of vector quantity
Magnitude and direction
Acceleration vector or scalar?
Vector
Mass scalar or vector
Scalar
Newton’s third law
Every action force has an equal and opposite reaction force
Newton’s second law
An object will accelerate in response to a resultant force
Newton’s first law
An object will remain its inertia until a net force is acted on the object.
Difference between elastic and in elastic collisions?
Elastic collision: kinetic energy before is equal to the kinetic energy afterwards
Inelastic collision: kinetic energy at the end is not equal to the kinetic energy at the start
Is linear momentum only conserved in elastic collisions
No, it is because linear momentum is always conserved
What can be described as the rate of change of momentum?
Force
Work done definition
Work done is the product of the magnitude of the force and distance moved by the object in the direction of the force. It is a measurement of energy and it’s units are joules with SI base unit kgm^2 s^-2
Rate of work done equal to
Power
Meaning of principle of conservation of energy
Energy cannot be created or destroyed, it can on,y be transferred into other forms of energy. The total energy in a closed system will always remain the same.
Definition of kinetic energy
The energy associated with the motion of an object with mass. The SI base unit is kgm^2s^-2
Definition of gravitation potential energy
The energy stored by an object at a point in a gravitational field.
Definition of elastic potential energy
The energy stored by an object as a result of a reversible change in an object’s shape
Efficiency
Useful/input * 100%
What is a moment? State the principle of moments
A turning force
Moment = force * perpendicular distance from the object
For an object in equilibrium the sum of the clockwise moments will equal the sum of the anti-clockwise moments.
Where is the “centre of gravity” on a uniform object
At its geometrical centre
