1) Potential energy before the fall: 98 J
The gravitational potential energy of an object is given by:
where m is the mass of the object, g is the gravitational acceleration and h the heigth of the object above the ground.
In this problem, m = 2 kg, g = 9.8 m/s^2 and h = 5 m: substituting into the equation, we find
2) Work done by gravity: 98 J
The work done by a force is given by:
where
F is the magnitude of the force
d is the displacement of the object
is the angle between the direction of the force and the displacement
In this problem:
d = 5 m
Therefore,
Calculator soup says the answer is 30.82
Answer:
A. Energy is lost when machines don't work right.
Explanation:
Energy cannot be created nor destroyed, according to the Law of Conservation of Energy.
Answer:
Kf= 36 J
W(net) = 32 J
Explanation:
Given that
m = 2 kg
F= 4 N
t= 2 s
Initial velocity ,u= 2 m/s
We know that rate of change of linear momentum is called force.
F= dP/dt
F.t = ΔP
ΔP = Pf - Pi
ΔP = m v - m u
v= Final velocity
By putting the values
4 x 2 = 2 ( v - 2)
8 = 2 ( v - 2)
4 = v - 2
v= 6 m/s
The final kinetic energy Kf
Kf= 1/2 m v²
Kf= 0.5 x 2 x 6²
Kf= 36 J
Initial kinetic energy Ki
Ki = 1/2 m u²
Ki= 0.5 x 2 x 2²
Ki = 4 J
We know that net work is equal to the change in kinetic energy
W(net) = Kf - Ki
W(net) = 36 - 4
W(net) = 32 J
