(13.89 - 5.56) m/s /30 s = 8.33 / 30 = 0.278 m/s^2
F = MA
F = 150 kg * 0.278 = 41.65 N
#2) Newton's Equations of motion
distance = 0.5 * acceleration * time^2 + original velocity * time
velocity = acceleration * time + original velocity
First we need acceleration
F = MA
7 N = 0.4 kg*A (NOTE: I converted to consistent units: kg, m, s)
A = 7/.4 = 17,5 m/s^2
V = at + Vo
80 m/s = 17.5 /s^2 * t + 0 (Started at rest)
80 = 17.5 t
t = 4.57 s
#3
First we need the weight of the book on the floor
F = MA (A = 9.8 m/s^2 the acceleration of gravity)
F = 0.4 kg * 9.8 m/s^2 = 3.92 N
Now we need the Net Force on the book slowing it down (A = - 1.5 m/s^2)
F = MA
F = 0.4 kg * 1.5 m/s^2 = 0.6 N
===> Friction is 0.6 N greater than your push or 5.6 N
Weird!!! That means friction is greater than the weight of the book
Mu (coff of friction) = Friction Force/Weight = 5.6 / 3.92 = 1,43 ( Nonsense answer)
#4 We can do as a ratio
70/400 = 1500/x
70 x = 600,000
x = 8,571 N
