[Async-2024-25] SPH4 ...

FRAMES OF REFERENCE

When analysing a problem, we need to establish a frame of reference. This defining a coordinate system. 

Our choice of frame of reference is important. We need to choose a frame of reference that will make solving the problem as easy as possible.

If the frame of reference is stationary or moving at a constant velocity, we call it a inertial frame of reference.

Newton's Laws are valid in all inertial frames of reference.

EXAMPLE PROBLEM #1

Mr Stone is going down an inclined ramp with an angle of \( 20^o \). If the ramp is \( 2.0 x 10^1 \) m long. How fast is he going at the bottom when he hits the curb (and, by Newton's 1st Law, how fast will he be thrown). Assume that his mass is 100 kg and the coefficient of friction of the wheels is 0.0100.

SOLUTION:

EXAMPLE PROBLEM #2

Mr Stone is now pushed down the hill with an applied force by his evil twin. He is travelling 18 m/s as he hits the curb. What was the magnitude of the applied force? [\( \mu = 0.0100, \Theta = 20^o, \Delta d = 2.0 x10^1 m, m=1.0x10^2 kg \)]

SOLUTION:

EXAMPLE PROBLEM #3

Mr. Stone is pushed up the hill with a velocity of 5.0 m/s (same hill \( \Theta=20^o \)). If the coefficient of friction between the cart and the hill si 0.10, how far up the hill will he travel until he stops?

SOLUTION: