Physics notes:
Newtons and work
Mass doesn’t directly affect velocity. It does directly affect inertia.
System-regularly interacting or interdependent group of items forming a unified whole
Two blocks on incline, string snaps, block went from moving forward, stop , then slide down.
Negative work when force is applied opposite to the direction of motion
In pulley system (like elevator when asked for work done by motor
Wnet = ΔEK
Wgravity + Wcountweight + Wmotor = 0
Wmotor = - (Wgravity + Wcountweight)
There are only six vector quantities :
Displacement (negative when moving backwards)
acceleration.
force.
momentum.
weight
velocity.
Free fall- Motion of an object under the influence of gravity/gravitational force/weight only
(Ball thrown from upward moving hot air balloon) Name and define in words the law that explains
why the ball first moves upwards immediately after it is dropped- Newton's First Law-A body will
remain in its state of rest or motion at a constant velocity unless a non-zero net/resultant force acts
on it.
Momentum unit is kg.m.s-1
Impulse unit is N.s
Using impulse momentum theory to explain why arrestor beds and seatbelts are used- both increase
the time over which the Fnet is applied thus reducing the Fnet applied as change in momentum
stays the same. (Fnet. T= change in momentum
, Terminal velocity- when an object falls at a maximum constant velocity
In hot air balloon problems the speed of the balloon is the vi of the ball or object.
For all equations of motion a direction must be chosen as positive or negative (either up or down or
left or right)
Work done on an object equals the energy transferred
Positive work done when angle of fapp is less than 90 degrees(positive work= energy
transferred.
0 work done at 90 degrees
Negative work done if fapp is applied at angle greater than 90 degrees
Use term ‘line absorption spectra’ when a glass prism is used to break apart light
FACTORS AFFECTING FRICTION-
Roughness/smoothness of the sliding object.
Roughness/smoothness of the surface.
Shape/design of the object.
Normal force acting upon the sliding bodies.( normal force is the force pushing the two
surfaces together, and the stronger the normal force, the stronger the force due to friction)
Dry friction is independent of the surface area of a contact.
Type of friction involved(rolling/sliding)
Inelastic collisions-energy not conserved. Elastic collisions- energy is conserved (calculate using ep
and ek and checking if initial equals final)
The area under an acceleration graph represents the change in velocity. The area under the net
force vs. time graph represents the change in momentum
Mechanical energy is conserved when ek is equal
Momentum is conserved when the conservation of momentum equation balances out
Translational kinetic energy is directly proportional to mass and the square of the magnitude of
velocity
Newtons and work
Mass doesn’t directly affect velocity. It does directly affect inertia.
System-regularly interacting or interdependent group of items forming a unified whole
Two blocks on incline, string snaps, block went from moving forward, stop , then slide down.
Negative work when force is applied opposite to the direction of motion
In pulley system (like elevator when asked for work done by motor
Wnet = ΔEK
Wgravity + Wcountweight + Wmotor = 0
Wmotor = - (Wgravity + Wcountweight)
There are only six vector quantities :
Displacement (negative when moving backwards)
acceleration.
force.
momentum.
weight
velocity.
Free fall- Motion of an object under the influence of gravity/gravitational force/weight only
(Ball thrown from upward moving hot air balloon) Name and define in words the law that explains
why the ball first moves upwards immediately after it is dropped- Newton's First Law-A body will
remain in its state of rest or motion at a constant velocity unless a non-zero net/resultant force acts
on it.
Momentum unit is kg.m.s-1
Impulse unit is N.s
Using impulse momentum theory to explain why arrestor beds and seatbelts are used- both increase
the time over which the Fnet is applied thus reducing the Fnet applied as change in momentum
stays the same. (Fnet. T= change in momentum
, Terminal velocity- when an object falls at a maximum constant velocity
In hot air balloon problems the speed of the balloon is the vi of the ball or object.
For all equations of motion a direction must be chosen as positive or negative (either up or down or
left or right)
Work done on an object equals the energy transferred
Positive work done when angle of fapp is less than 90 degrees(positive work= energy
transferred.
0 work done at 90 degrees
Negative work done if fapp is applied at angle greater than 90 degrees
Use term ‘line absorption spectra’ when a glass prism is used to break apart light
FACTORS AFFECTING FRICTION-
Roughness/smoothness of the sliding object.
Roughness/smoothness of the surface.
Shape/design of the object.
Normal force acting upon the sliding bodies.( normal force is the force pushing the two
surfaces together, and the stronger the normal force, the stronger the force due to friction)
Dry friction is independent of the surface area of a contact.
Type of friction involved(rolling/sliding)
Inelastic collisions-energy not conserved. Elastic collisions- energy is conserved (calculate using ep
and ek and checking if initial equals final)
The area under an acceleration graph represents the change in velocity. The area under the net
force vs. time graph represents the change in momentum
Mechanical energy is conserved when ek is equal
Momentum is conserved when the conservation of momentum equation balances out
Translational kinetic energy is directly proportional to mass and the square of the magnitude of
velocity
