Answer:
Rest and motion are the relative terms because they depend on the observer's frame of reference. So if two different observers are not at rest with respect to each other, then they too get different results when they observe the motion or rest of a body.
Answer: 
Explanation:
Given
Length of plank is 1.6 m
Force 
is applied on the left side of plank
Force 
is applied 43 cm from the left end O.
Mass of the plank is 
for equilibrium
Net torque must be zero. Taking torque about left side of the plank
Net vertical force must be zero on the plank
Distance, since distance represents how far something has travelled, which would be in our case 2.5m.
Answer:
0.31 m
Explanation:
m = mass of the block = 1.5 kg
H = height from which the block is released on ramp = 0.81 m
k = spring constant of the spring = 250 N/m
x = maximum compression of the spring
using conservation of energy
Spring potential energy gained by spring = Potential energy lost by block
(0.5) k x² = mgH
(0.5) (250) x² = (1.5) (9.8) (0.81)
x = 0.31 m
0.25 m/s squared
hope this helps x
