physics - motion

1. Use the formula: work done = change of kinetic energy
i.e. force x distance = change of kinetic energy
F x (1.8/100) = (1/2) x 930 x (47x1000/3600)^2
solve for F

2. Net force on the passenger = 1.45mg - mg = 0.45 mg
where m is the mass of the passesnger and g is the acceleration due to gravity

using force = mass x acceleration
acceleration (of lift) = 0.45mg/m = 0.45g
use equation of motion: v^2 = u^2 + 2.a.s
with u = 0 m/s, s = 3.7 m, a = 0.45g, v = ?
hence, v^2 = 2 x 0.45g x 3.7
solve for v

3. 450 rev/ min = 450 x 2 x pi/60 radians/s = 15.pi rad/s
where pi = 3.14159.....

Radial acceleration = 3.4 x (15.pi)^2 m/s2
= [3.4 x (15.pi)^2/g]g