Answer:
Some work input is lost to friction
Explanation:
The efficiency of a machine is defined as:
(1)
where
is the work output
is the work input
Due to the law of conservation of energy, the work output can never be larger than the work input (because energy cannot be created). Moreover, in real machines part of the work input is lost due to the presence of frictions: as a result, part of the energy in input is converted into thermal energy or other forms of energy, and so the work output is smaller than the work input, and so the ratio (1) becomes less than 1, and so the efficiency is less than 100%.
Potential energy is measured by mass * gravity * height. So, the larger the mass on a roller coaster, the more potential energy it has.
Also, the higher it is, the more potential energy it has.
Answer:
True
Explanation:
- A conservative force is a force whose work done does not depend on the path taken, but only on the final and starting point.
- The mechanical energy of an object is defined as the sum of the kinetic energy (K) and the potential energy (U): E = K + U
- The law of conservation of energy states that, in case only conservative forces are acting on the object, the mechanical energy of the object E is conserved
- In case non-conservative forces are acting on the object, the mechanical energy is no longer constant. An example of non-conservative force is the force of friction: when the force of friction is acting on a car in motion, the car is slowed down by the effect of the force, losing some of its kinetic energy, K. If the car is travelling on a flat road, then its potential energy U does not change: this means that the mechanical energy of the car, E, is decreasing, so it is no longer conserved.
A). The apple has thermal energy, because its temperature is higher
than absolute zero.
It also has chemical energy, because if I eat it, I get a burst of energy
and I become ambitious for a while.
It also has gravitational potential energy, because if I drop it on my foot,
it could bruise one of my piggies.
b). I could increase its potential energy by lifting it higher, like over my head.
c). As long as I'm just holding the apple, it doesn't have any kinetic energy.
I could give it some kinetic energy by throwing it.
Or I could just drop it, and let gravity give it kinetic energy.