20km every 1 hr is what 20km/hr means.
so 3hrs is 20km*3=60km.
same but who knows how 2021 might go
ΔU =
-Wint
Consdier the work of of
interaction is W =m*g*h - equation -1
and the Potential energy U.
Final Potential energy Uf =0
, And the Initial Potential Energy Ui =m*g*h
<span>Now we will write the
equation for a Change in Potential energy ΔU,</span>
ΔU = Uf
- Ui
= 0-m*g*h
<span> ΔU = -m*g*h --Equation 2</span>
Now compare the both equation
<span>Wint = -ΔU</span>
we can rewrite the above
equation
ΔU =
-W.
<span>So our Answer is ΔU = -W. .</span>
<span> </span>
As long as it sits on the shelf, its potential energy
relative to the floor is . . .
Potential energy = (mass) x (gravity) x (height) =
(3 kg) x (9.8 m/s²) x (0.8m) = <u>23.52 joules</u> .
If it falls from the shelf and lands on the floor, then it has exactly that
same amount of energy when it hits the floor, only now the 23.52 joules
has changed to kinetic energy.
Kinetic energy = (1/2) x (mass) x (speed)²
23.52 joules = (1/2) x (3 kg) x (speed)²
Divide each side by 1.5 kg : 23.52 m²/s² = speed²
Take the square root of each side: speed = √(23.52 m²/s²) = <em>4.85 m/s </em> (rounded)
