When balanced forces follow up on an object, the object won't move. If you push against a wall, the wall pushes back with an equal but opposite force. Neither you nor the wall will move. Forces that cause a change in the motion of an object are unbalanced forces.
The answer is 4.0 kg since the flywheel comes to rest the
kinetic energy of the wheel in motion is spent doing the work. Using the
formula KE = (1/2) I w².
Given the following:
I = the moment of inertia about the
axis passing through the center of the wheel; w = angular velocity ; for the
solid disk as I = mr² / 2 so KE = (1/4) mr²w². Now initially, the wheel is spinning
at 500 rpm so w = 500 * (2*pi / 60) rad / sec = 52.36 rad / sec.
The radius = 1.2 m and KE = 3900 J
3900 J = (1/4) m (1.2)² (52.36)²
m = 3900 J / (0.25) (1.2)² (52.36)²
m = 3.95151 ≈ 4.00 kg
The advantages of generating electricity using a hydroelectric power station rather than wind turbines is that it's not polluting anything since it's regular water. It also can be used over and over again.
The disadvantages of using a hydroelectric power station is that it can be very deadly and cause damage to towns if it overfills or falls apart releasing all the water. Since nothing lasts forever, eventually they will break apart and would require everyone to evacuate before doing so. Another disadvantage is that it disrupts migration of animals that live in the water such as fish.
It's better than wind turbines because wind turbines require a lot of wind to turn and on days without wind, very little energy can be produced.
Answer: 50 gram superball that strikes the wall at 1 m/s and bounces away at 0.8 m/s has greater change in kinetic energy.
Explanation:
50 gram superball that strikes the wall at 1 m/s and bounces away at 0.8 m/s has the greater change in kinetic energy because the collision is elastic in nature that is bodies separates after collision and doesn't lose any kinetic energy.
Also for an elastic collision, both the momentum and energy of the bodies are conserved compare to inelastic collision where only momentum is conserved but not the kinetic energy(this is attributed to bodies that sticks together after collision).
