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zzz [600]
4 years ago
10

We know that the law of conservation of energy states that energy can not be created or destroyed. It only changes form. Conside

r this energy transformation diagram. Assume that the energy input in this case is chemical potential energy and the useful energy output is kinetic energy, specifically a small fan to keep you cool. The diagram also shows how to calculate the efficiency of the fan. If the law of conservation of energy holds true, explain why the efficiency of the fan is not 100%.
Physics
2 answers:
Pavel [41]4 years ago
7 0

The conservation of energy always holds true even when not clearly observable in machines that are less than 100% efficient. More often than not a machine will suffer energy losses (e.g. consider for a cooling fan: friction between the rotating blades, drag resistance in the air the fan is pushing around, resistance in the wire, and heat radiating/conducting away from the circuitry).

Ierofanga [76]4 years ago
3 0

Answer:

Due to energy loss.

Explanation:

The law of conservation of energy states that energy can neither be created nor be destroyed. It can only change its states from one energy state to another.

The efficiency is defined as the ratio of output work to the input work. The efficiency of the fan is not 100%. Because some of the energy is lost in the form of heat and sound. No machine is 100% efficient. There is always some loss of energy takes place.

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A 75.0-kg ice skater moving at 10.0 m/s crashes into a stationary skater of equal mass. After the collision, the two skaters mov
Ksenya-84 [330]

Answer:

Explanation:

Momentum change for either skater is mΔv = 75.0(5.0) = 375 kg•m/s

As a change in momentum is equal to an impulse

375 = FΔt

F = 375/0.100 = 3750 N

As 3750 N < 4500 N no bones are broken.

4 0
3 years ago
If each of the three rotor helicopter blades is 3.50 m long and has a mass of 120 kg , calculate the moment of inertia of the th
devlian [24]

Answer:

1470kgm²

Explanation:

The formula for expressing the moment of inertial is expressed as;

I = 1/3mr²

m is the mass of the body

r is the radius

Since there are three rotor blades, the moment of inertia will be;

I = 3(1/3mr²)

I = mr²

Given

m = 120kg

r = 3.50m

Required

Moment of inertia

Substitute the given values and get I

I = 120(3.50)²

I = 120(12.25)

I = 1470kgm²

Hence the moment of inertial of the three rotor blades about the axis of rotation is 1470kgm²

7 0
3 years ago
In a lab, the mass of object A is 2.5 kg. Object A weighs:
dangina [55]

Answer:

25N

Explanation:

Assuming the lab is on earth:

w = mg = 2.5 (9.81) = 25N

8 0
3 years ago
Identify each part of this chemical equation that describes the burning of methane and oxygen. B (blue box): D (number): E (purp
Allushta [10]

Answer:

The correct answer is -

A (the entire green box): Chemical Equation

B (the blue box): Reactants

C (the arrow): Reacts to Form

D (the number): Coefficient

E (the purple box): Products

Explanation:

The chemical reaction of burning methane and oxygen is as follows;

Here, the green part A is the chemical equation that includes various parts that are reactants B, methane, and oxygen, C is an arrow that indicates the formation of products.

2 is here coefficient that indicates the moles of the oxygen which forms carbon dioxide and water in box E is products

5 0
3 years ago
An Atwood machine is constructed using a hoop with spokes of negligible mass. The 2.3 kg mass of the pulley is concentrated on i
Sergeu [11.5K]

Answer:

a = 2.77~{\rm m/s^2}

Explanation:

Since the pulley has a mass concentrated on its rim, the pulley can be considered as a ring.

The moment of inertia of a ring is

I = mr^2 = (2.3)(23.5\times 10^{-2})^2 = 0.127

The mass on the left is heavier, that is the pulley is rotating counterclockwise.

By Newton's Second Law, the net torque is equal to moment of inertia times angular acceleration.

\tau = I \alpha

Here, the net torque is the sum of the weight on the left and the weight on the right.

\tau = m_1gR - m_2gR = (1.65)(9.8)(23.5\times 10^{-2}) - (1)(9.8)(23.5\times 10^{-2}) = 1.497~{\rm Nm}

Applying Newton's Second Law gives the angular acceleration

\tau = I\alpha\\1.497 = 0.127\alpha\\\alpha = 11.78~{\rm rad/s^2}

The relation between angular acceleration and linear acceleration is

a = \alpha R

Then, the linear acceleration of the masses is

a = 11.78 \times 23.5\times 10^{-2} = 2.77~{\rm m/s^2}

5 0
3 years ago
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