Respuesta :
Lets see:-
We have our formula for potential energy, which we are trying to solve for,
PE = mgh or potential energy = mass * gravity * height
So we know that PE all depends on these.
Height : 30 meters
Mass : 25 kg
Gravity (which is always constant) : 9.8 m/s/s
Now add into formula.
PE = 25*30*9.8
PE = 7350 Joules
Answer: PE = 7350 Joules
We have our formula for potential energy, which we are trying to solve for,
PE = mgh or potential energy = mass * gravity * height
So we know that PE all depends on these.
Height : 30 meters
Mass : 25 kg
Gravity (which is always constant) : 9.8 m/s/s
Now add into formula.
PE = 25*30*9.8
PE = 7350 Joules
Answer: PE = 7350 Joules
Potential energy =
(mass) x (gravity) x (height above the reference level) .
Relative to the bottom of the cliff, the potential energy
at the top of the cliff is
(25kg) x (9.8 m/s²) x (30 meters)
= (25 x 9.8 x 30) kg-m²/s²
= 7,350 joules .
Kinetic energy = (1/2) x (mass) x (speed²)
The rock's kinetic energy at the bottom is
the same as its potential energy at the top.
7,350 joules = (1/2) x (25 kg) x (speed²)
Divide each side
by 12.5kg : 7,350 joules/12.5 kg = speed²
7,350 kg-m²/s² / 12.5kg = speed²
(7,350 / 12.5) m²/s² = speed²
588 m²/s² = speed²
Take the square root
of each side:
Speed = √(588 m²/s²)
= 24.248... m/s (rounded)