Asmall rock is thrown vertically upward with a speed of 21.0 m/s from the edge of the roof of a 35.0-m-tall building. the rock doesn't hit the building on its way back down and lands in the street below. ignore air resistance.(a) what is the speed of the rock just before it hits the street? (b) how much time elapses from when the rock is thrown until it hits the street?

a) Vf = 33.78m/s

b) t = 5.478s

Explanation:

We can calculate final speed using:

where Vo = 21m/s;  g = 10m/s2;   ΔY = -35m

Vf = 33.78m/s

Now, having final speed, we can calculate the amount of time elapsed:

Vf = Vo - g * t    where Vf = -33.78m/s;   Vo = 21m/s;   g = 10m/s2

t = 5.478s

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force