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2 years ago

I would appreciate some help.

1 answer:

4 0

You oughtta be able to do this one.

The "efficiency" is just the portion of the input work that
comes out in a useful form.

If the efficiency is 70%, that tells you that however much work
you put INto the machine, the machine will do 70% of that much
work for you at the output side.

Put 20,000 J in ... out comes (0.70) x (20,000 J) = 14,000 J .

What happens to the other 30% of the work you put into it ?
It turns into HEAT. That's why machines always have to be
cooled somehow while they're running.

You might be interested in

The driver of a car traveling at 23.1 m/s applies the brakes and undergoes a constant

Vsevolod [243]

Answer:

The tires make 125 revolutions before the car stops

Explanation:

Circular and Linear Motion

A tire rotates around a fixed point and the tire when in contact with the ground, drives a vehicle in a linear path. This is an example of a relationship between both types of movements that can be taking place simultaneously.

The car is moving with an initial speed of $v_o=23.1\ m/s$ and then breaks at $a=-1.03\ m/s^2$ until it stops. We can compute the time take to stop by using

$\displaystyle v_f=v_o+a.t$

Solving for t

$\displaystyle t=\frac{v_f-v_o}{a}$

Putting in numbers

$\displaystyle t=\frac{0-23.1}{-1.03}$

$\displaystyle t=22.427\ sec$

Now, let's transfer this information to the circular motion. We know the tangent speed is

$\displaystyle v_t=w.r$

Being w the angular speed and r the radius of the circle, in this case, the tires. The tangent speed is the same as the speed of motion of the car. It gives us the initial angular speed

$\displaystyle w_o=\frac{v_t}{r}$

$\displaystyle w_o=\frac{23.1}{0.33}=70\ rad/s$

When the circular motion is not uniform, i.e. there is angular acceleration $\alpha$ , the angular speed is a function of time

$\displaystyle w=w_o+\alpha t$

We can compute the angular acceleration knowing the final angular speed is zero when the car stops.

$\displaystyle \alpha=\frac{w-w_o}{t}=\frac{0-70}{22.427}$

$\displaystyle \alpha=-3.121\ rad/s^2$

The rotation angle is also a function of time as shown

$\displaystyle \theta=w_o\ t+\frac{\alpha t^2}{2}$

Using the given and computed values

$\displaystyle =70(22.427)-\frac{3.121(22.427)^2}{2}$

$\displaystyle \theta =784.95\ rad$

Knowing each revolution is $2\pi$ radians, the number of revolutions is

$\displaystyle n=\frac{\theta }{2\pi}=125\ rev$

The tires make 125 revolutions before the car stops

8 0

3 years ago

A) a 50 kg gymnast jumps from the balance beam with a speed of 1.7m/s. she lands upright on the ground 124cm below. At what spee

ivolga24 [154]

PART a)

By energy conservation we can say

$PE_i + KE_i = PE_f + KE_f$

$mgh_1 + \frac{1}{2}mv_i^2 = mgh_2 + \frac{1}{2}mv_f^2$

divide whole equation by mass "m" and plug in all given data

$9.8(1.24) + \frac{1]{2}(1.7)^2 = 9.8(0) + \frac{1}{2}(v)^2$

$v_f = 5.21 m/s$

so gymnast will reach the floor with speed 5.21 m/s

PART b)

Now the gymnast bend her knees by 0.1 m and comes to rest

so here we will have

$v_f^2 - v_i^2 = 2 a d$

$0 - 5.21^2 = 2(a)(0.1)$

$a = 135.97 m/s^2$

now the force on the gymnast will be

$F = ma$

$F = 50 \times 135.97 = 6798.5 N$

so during landing the force will be 6798.5 N

5 0

2 years ago

100 POINTSSSS PLEASE HELP

lara31 [8.8K]

Wood, wind, sunshine,geothermal energy, biomass and water

4 0

2 years ago

Read 2 more answers

A system in which only one particle can move has the potential energy shown in (figure 1). Suppose u1 = 60 j. What is the y-comp

marta [7]

The y-component of the force on the particle at the given position is 120 N.

<h3>Electric force on the particle</h3>

The electric force on the particle is determined by applying Coulomb's law and work-energy theorem as shown below;

Fd = W

Where;

F is the applied force
d is the distance
W is potential

F = W/d

F = 60/0.5

F = 120 N

Thus, the y-component of the force on the particle at the given position is 120 N.

Learn more about electric force here: brainly.com/question/20880591

3 0

1 year ago

100 J OF HEAT IS PRODUCED EACH SECOND IN A 4 COULUMB RESISTER. THE POTENTIAL DIFFERANCE ACROSS THE RESISTER WILL BE

igomit [66]

Answer:

The correct answer is "20 Volts".

Explanation:

Given:

Heat,

H = 100 J

Resistance,

R = 4 Ω

As we know,

⇒ $P=\frac{v^2}{R}$

By putting the values, we get

⇒ $100=\frac{v^2}{4}$

⇒ $v^2=100\times 4$

⇒ $=400$

⇒ $v=\sqrt{400}$

⇒ $=20 \ volts$

6 0

2 years ago