MCAT Physics 2

A field that exists between any two objects with mass.

An invisible influence that can exert a force on a mass or charge.

(In space)

F = mg

(Near earth)

(In space)

PE = mgh

(Near earth)

• Friction opposes sliding not motion.
• If there is sliding, it's kinetic friction; if there's no sliding, it's static friction.
• Static µ is always greater than kinetic µ.
• Surface area does not increase friction when the mass is the same.

F_f = µ_(s/k)F_N

F_f = µ_(s/k)mgcos

F = mgsin

F_N = mgcos

V_f = √(2gh)

F = k∆x

• x - displacement
• k - spring constant

T = 2π√(m/k)

(mass on a spring)

T = 2π√(L/g)

(pendulum)

• T - period (time/wave)
• m - mass
• k - spring constant
• L - length of pendulum
• g - gravity

• Terminal velocity
• Constant velocity
• Objects at rest
• Balanced fulcrums or boards on strings
• Objects floating in liquid

• T = F
• T = mg
• T = Frsin

• - lever arm
• r - distance between the force and the point of rotation.
• rsin - always equals , but r = only when = 90˚

Equilibrium - list all the forces and put them equal to one another.

Not Equilibrium - list all the forces and add "ma" to the loosing side.

If a string is pulling a ball into a circular motion, the string's force on the ball is centripetal and the ball's force on the string is centrifugal.

Centrifugal does not exist.

• - angular frequency (rad/s)
• v - tangential velocity (m/s)
• r - radius (m)
• f - frequency (Hz)

For the MCAT angular frequency and angular velocity are synonymous.

• An object is in rotational equilibrium if:
• 1. It is NOT rotataing
• 2. It is rotating with a constant angular velocity/frequency

momentum is inertia increased by velocity and is always conserved (remains constant) in an isolated system.

• Impulse = ∆
• Impulse = m∆v
• Impulse = F_avgt

• If there is no change in velocity, there can be no impulse.
• The greater the change in velocity the greater the change in impulse.

• (KE₁ + KE₂)_before + (KE₁ + KE₂)_after
• In elastic collisions momentum and energy are both conserved.

m₁v₁ + m₂v₂ = m₁v₁ + m₂v₂

In inelastic collisions momentum is conserved but energy is not. For perfectly inelastic collisions the equations becomes:

m₁v₁ + m₂v₂ = (m₁ + m₂)v₃

Force/Area

∆dimension/original dimension

stress/strain

• Young's modulus - simultaneous pushing or pulling, perfectly lined up with one another.
• Shear modulus - simultaneous pushing or pulling not perfectly lined up.
• Bulk modulus - simultaneous compression from all sides.

∆L = L_o∆T

• T - temperature
• L - length in inches
• - coefficient of thermal expansion

The energy of internal vibrations of molecules or atoms within a system.

Energy dissipated as heat. On the MCAT this usually means heat dissipated from a collision.

Heat energy and internal energy are almost synonymous.

The energy contained within chemical bonds, or the energy stored/released due to the separation and/or flow of electrons.

ME = KE + PE

• W = ∆Energy
• W = Fdcos

Units - Joules () or ()