Physics - Final Flashcards
What is the distance formula?
Df = di + vt + 1/2at²
What is terminal velocity? (3)
Is work being done?
When the upward forces of air resistance balances the downward force of gravity
Net force = 0
Yes, work is being done, because the object’s gravity moves the object downward with a constant maximum speed, and the forces are getting balanced out by air resistance
Scalar vs vector
Scalar - only has magnitude
Vector - magnitude and direction
The quadratic equation is used with values in which direction?
The y-direction
What is the path of a projectile called?
What shape does it form? (2)
A trajectory
Parabola
What is Newton’s second law? (2)
F = ma
Measured in Newtons –> kg•m/s²
What is the fundamental unit of force? (2)
F = ma F= kg•m/s² or N
When an object is moving at constant velocity, how do you determine net force? (2)
Net force = 0
A = 0
Define inertia
Describes how much it will resist change to the motion of the object
What is the formula for the weight of an object directed down an inclined plane
Weight = mass • gravity
Units of the coefficient of friction?
There are no units
How to find the angle of slippage if given the coefficient of static friction
Ff = μsFn –> μsmgcosθ –> Ff/μsmg = cos θ⁻1
List the 3 types of friction in order of weakest to strongest (3)
- Rolling
- Kinetic
- Static
When an object begins to slide down a ramp, which two forces are equal?
The x and y components
What is the equation for the force of kinetic friction on a flat surface?
μkmg
Unit for energy?
Joule
What is the conservation of energy equation for the velocity of an object at the bottom of the ramp (with friction)? (2)
PE - Ff = KE
V= √2g(h-μkcosθd)
What is the formula for work done by friction down an inclined plane?
Wf = μkmgcosθd
What are the fundamental units of power? (2)
P = w/t –> kg•m²/s³
W= fd –> kg•m²/s²
If the sun were to suddenly disappear, what would happen to the path of the earth?
It would go in a straight line
Under what circumstances will the quadratic formula provide two real roots?
When an object passes a certain point twice
The metric system
Based on powers of 10
10mm = cm
10mm = 1cm
10cm = dm
10cm = 1 dm
10dm =
10dm = 1m
Basic trig functions (4)
Tan θ = Δy / Δx
D = √Δx²+Δy²
Sin θ = Vy/V or Δy/d
Cos θ = Vx/V or Δx/d
Matric prefixes (9)
Nano- 10⁻⁹ Micro- 10⁻⁶ Milli- 10⁻³ Centi- 10⁻² Deci- 10⁻¹ Deka- 10 Kilo- 10³ Mega- 10⁶ Giga- 10⁹
Calculating line of best-fit (2)
Calculate by using y=mx+b
y-y₁=m(x-x₁)
Distance vs displacement (2)
Distance - total distance traveled
Displacement - change in position of an object
Speed vs velocity (2)
Speed - scalar quantity
Velocity - vector quantity
Velocity vs acceleration (2)
Velocity - rate of change in distance
Acceleration - rate of change in velocity
How to find X and Y components (4)
Vx = dx/t Vy = dy/t
Vx = Vcosθ Vy = Vsinθ
How to solve advanced projectile motion problems? (3)
- find x component using dx=Vx•t
- Find velocities for x and y component using Vx=V(cosθ) and Vy=V(sinθ)
- Find t using distance formula going in the y-direction –> dfy=diy+vt+1/2at²
Projectile motion
Refers to the motion of an object that is thrown, or projected into the air at an angle
Free-fall acceleration
The vertical motion of a projectile with a constant downward acceleration due to gravity
Direction of gravity? (2)
Downwards; not horizontally at all
There are two objects: one is thrown and one is dropped. Which one will land with the shortest time?
They will finish landing with the same time
What are the circumstances for negative velocities?
Velocities are negative as an object goes back down
How the distance formula can be reduced to simpler forms? (2)
D = 1/2at²
T = √2d/g
Resultant
The hypotenuse of a Pythagorean theorem triangle
What is Newton’s first law?
Law of inertia - an object at rest tends to stays at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force
Define weight
A measure of the force of gravity on the mass of an object
What is Newton’s third law?
For every action there is an equal and opposite reaction
Net force (4)
Causes acceleration
No acceleration = no net force
Net force = acceleration/mass
Net force = mgcosθ + mgsinθ
What force is ignored in projectile problems?
Air-resistance
Action-reaction pair “force pairs”
A pair of simultaneous equal but opposite forces resulting from the interaction of two objects
Static friction (5)
The resistive force that opposes the relative motion of two contacting surfaces that are at rest with respect to one another
A = 0
Net force = 0
The friction caused by the microwelds is the opposing force that cancels out the force applied
Ex. A boy pushing a box but it is not moving
Kinetic friction
How is kinetic friction caused? (2)
The resistive force that opposes the relative motion of two contacting surfaces that are moving past one another
Caused by microwelds breaking and then forming again as two surfaces rub against each other
The normal force (Fn) (2)
The supporting force that acts on the object perpendicular to the surface plane
Fn = mg
Friction
A resistive force that acts in a direction opposite to the direction of the relative motion of two contacting surfaces
What causes friction?
Microwelds; two bumpy surfaces that rub up against each other and stick together to produce microwelds
How to calculate the force of friction? (Ff)
Ff = μFn –> μmgcosθ
How to find the coefficient of kinetic friction? (3)
μk = Fk/Fn
Fk = μkmg
Fn = mg
How to solve tension problems (5)
- Set forces in x and y equal
Ty₁ + Ty₂ = mg
Tx₁ = Tx₂ - Put Ty₁, Ty₂, Tx₁, and Tx₂ in terms of T₁ and T₂
T₁sinθ + T₂cosθ = mg
3. Set T₁ in terms of T₂ and Substitute
Because T₁ = T₂, this is possible.
Do T₁sinθ₁ + T₂sinθ₂ = mg
4. Solve for T₁
5. Go back and solve for T₂
T₁ = (T₂cosθ)/ cosθ
Define force
The cause of an acceleration or the change in an objects velocity
Define energy
The ability to change or cause change
No energy =
No energy = no change
Potential (4) vs kinetic energy (3)
Potential:
- energy of what might happen
- potential to change
- unit = Joule (kg•m²/s²)
- Ep = mgh
Kinetic:
- energy of motion
- unit = Joule
- Ek = 1/2mv²
Define work (3)
A transfer of energy
W = force x distance
Unit = Joule = 1 N • m
Only done when components of a force are parallel to a displacement
What results from no work being done?
No change in kinetic energy and potential energy = no work done
How to find work done by a constant force?
W = Fd(cosθ)
How to find the net work done by a constant net force?
Wnet = Fnet•d•(cosθ) –> μkmgcosθd
Other ways to find net work? (2)
Wnet = m[(Vf²-Vi²)/2]
Wnet = ΔKE (change in kinetic energy)
Gravitational potential energy (3)
The potential energy associated with an object due to the position of the object
PEg = mgh
H = 0
Power (5)
Rate at which energy is transferred
P= work/time
P= kg•m²/s³ (Watts)
P = F(d/t) <—- W=Fd
P = Force•velocity
Conservation of energy
Energy can change form; it can’t be destroyed nor created
Where does missing energy go? Possible sources of “lost energy”? (3)
Friction
Gravity / free-fall acceleration
Air resistance***
Similarities and differences between work and force? (2)
Similarities- both involve forces that cause accelerations
Differences - can have a force w/ no motion, but you can’t have WORK w/o motion
How is power related to work and forces?
Power is the rate at which work is being done and work involved forces
When the net work of an object = 0… Is the object moving?
Needs more info. It can be moving at a constant velocity or it could be standing still
When would you set forces equal to each other? (3)
When velocity is constant
When acceleration = 0
When Fnet = 0
Dimensional analysis of PE, KE, work, and power? (4)
PE = mgh –> kg•m²/s²
KE = 1/2mv² –> kg•m/s²
Work = Fd –> kg•m²/s²
Power = w/t –> kg•m²/s³
How to find force at an angle?
F = mgsinθ
How to find a using force at an angle?
A = gsinθ
How to find work done by someone
W = Fd
How to find work done by gravity
W = mgh
How to find x and y components of work? (2)
Wx = mgcosθd
Wy = mgsinθd
Weight down an inclined plane
Mgsin = weight down an inclined plane
