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2 years ago

Effieciency of a machine is never 100%

Physics

1 answer:

tatyana61 [14]2 years ago

4 0

Answer:

in real life yes it's true because of energy lost in another way that we do not want. like car engine lost some energy as heat. So the energy from gasoline can't converted 100% to move the tire. Maybe it only 40-60 % energy use for move and the rest lost as heat and other

but sometime it can be 100% of efficiency on physics text book so that we can learn physics in the easiest way.

You might be interested in

State three differences between solid friction and viscosity

Mrrafil [7]

Difference between solid friction and viscosity is as follows: Viscosity is proportional to the surface area whereas solid friction is independent of area of solid surfaces in contact. Viscous force on the body depends upon its velocity in the viscous media. But, friction does not depend on the velocity of the body.

8 0

1 year ago

The amount of work done by two boys who apply 200 N of force in an

Aleksandr [31]

The amount of work done by two boys who apply 200 N of force in an unsuccessful attempt to move a stalled car is 0.

Answer: Option B

<u>Explanation: </u>

Work done is the measure of work done by someone to push an object from its present position. We can also define work done as the amount of forces needed to move an object from its present position to another position. So the amount of work done is directly proportionate to the product of forces acting on the object and the displacement of the object.

$\text { Work done }=\text { Force } \times \text { displacement }$

So in this present case, as the two boys have done an unsuccessful attempts to push a stalled car so that means the displacement of the car is zero as there is no change in the position of the car. But they have applied a force of 200 N each. So the amount of work done will be

$\text { Work done }=200 \mathrm{N} \times 0=0$

Thus, the amount of work done by two boys will be zero due to their unsuccessful attempt to move a stalled car.

8 0

2 years ago

A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting

rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is $\sqrt{725}$ ft/ sec

Explanation:

Given:

h(t) = 25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

$D(t) = \sqrt{h^2 + x^2}$

Lets find the derivative of distance with respect to time

$\frac{dD}{dt} (t) = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}$

Substituting the values of h(t) and x(t) and simplifying we get,

$\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}$

$\frac{dh}{dt} = 25ft/sec$

$\frac{dx}{dt} = 10 ft/sec$

$\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}$ = $\frac{725}{\sqrt{725}}$ = $\sqrt{725}$ ft / sec

5 0

2 years ago

Which statements describe what is occurring at t=5 seconds? Check all that apply

Alex73 [517]

Answer: The object changed directions

The object sped up

Explanation:

7 0

2 years ago

According to the concept of length contraction, what happens to the length of an object as it approaches the speed of light and

lord [1]

When an object moves its length contracts in the direction of motion. The faster it moves the shorter it gets in the direction of motion.
The object in this question moves and then stops moving. So it's length first contracts and then expands to its original length when the motion stops.
The speed doesn't have to be anywhere near the speed of light. When the object moves its length contracts no matter how fast or slow it's moving.

8 0

3 years ago