Physics 121

Trig

sin q = o/h

cos q = a/h

tan q = o/a

area = pr² (circle)

Kinematics

v = Dx/Dt

a = Dv/Dt

Dx = v_ot + ½ at²

v_f² = v_o² + 2aDx

g = 9.8 m/s²

Dynamics

F_net = ma

F_g = Gm₁m₂/r²

F_g = mg (near surface of earth)

f_k = m_k F_N

f_s < m_s F_N

a_c = v²/r =w²r

Work and Energy

W = Fd cos q

KE = ½ m v²

W_net = DKE

W_nc = DKE + DPE

PE = mgh

Impulse and Momentum

Impulse = F t = Dp

p = mv

m₁v₁ + m₂v₂ = (m₁+m₂)v_f (Inelastic)

V_cm = Sm_iv_i/Sm_i

Elastic Collisions

1) Find V_cm

2) Subtract V_cm from each velocity

3) Change sign of each velocity

4) Add V_cm to each velocity

Rotations

Rolling without slipping

x = qr

v = wr

a = ar

X_cm = Sm_ix_i/Sm_i

Dq = w_ot + ½ at²

w_f² = w_o² + 2aDq

w = Dq/Dt

a = Dw/Dt

KE = 1/2Iw²

t_net = I a

t = f(Dx) sinq

I = mr²

l = Iw (Angular momentum)

Springs

F = -kDx

PE = ½ k Dx²