Ask question

Ask question

All categories

2 years ago

3

The input work on a pulley system is 75 J. If the pulley system is 84 percent efficient, then what is the output work from the p

ulley system?

1 answer:

romanna [79]2 years ago

7 0

Answer: 63 J

Explanation:

The effiency ( $E$ ) of a machine is given by the ratio between the output work $W_{out}$ and the input work $W_{in}$ :

$E=\frac{W_{out}}{W_{in}}$

Where:

$E=84\%=0.84$

$W_{in}=75 J$

Isolating $W_{out}$ :

$W_{out}=E W_{in}$

$W_{out}=(0.84)(75 J)$

Finally:

$W_{out}=63 J$

You might be interested in

When two resistors are wired in series with a 12 V battery, the current through the battery is 0.33 A. When they are wired in pa

MA_775_DIABLO [31]

Answer:

If R₂=25.78 ohm, then R₁=10.58 ohm

If R₂=10.57 then R₁=25.79 ohm

Explanation:

R₁ = Resistance of first resistor

R₂ = Resistance of second resistor

V = Voltage of battery = 12 V

I = Current = 0.33 A (series)

I = Current = 1.6 A (parallel)

In series

$\text{Equivalent resistance}=R_{eq}=R_1+R_2\\\text {From Ohm's law}\\V=IR_{eq}\\\Rightarrow R_{eq}=\frac{12}{0.33}\\\Rightarrow R_1+R_2=36.36\\ Also\ R_1=36.36-R_2$

In parallel

$\text{Equivalent resistance}=\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}\\\Rightarrow {R_{eq}=\frac{R_1R_2}{R_1+R_2}$

$\text {From Ohm's law}\\V=IR_{eq}\\\Rightarrow R_{eq}=\frac{12}{1.6}\\\Rightarrow \frac{R_1R_2}{R_1+R_2}=7.5\\\Rightarrow \frac{R_1R_2}{36.36}=7.5\\\Rightarrow R_1R_2=272.72\\\Rightarrow(36.36-R_2)R_2=272.72\\\Rightarrow R_2^2-36.36R_2+272.72=0$

Solving the above quadratic equation

$\Rightarrow R_2=\frac{36.36\pm \sqrt{36.36^2-4\times 272.72}}{2}$

$\Rightarrow R_2=25.78\ or\ 10.57\\ If\ R_2=25.78\ then\ R_1=36.36-25.78=10.58\ \Omega\\ If\ R_2=10.57\ then\ R_1=36.36-10.57=25.79\Omega$

∴ If R₂=25.78 ohm, then R₁=10.58 ohm

If R₂=10.57 then R₁=25.79 ohm

6 0

2 years ago

Daniel is 50.0 meters away from a building. He observes that his line-of-sight to the tip of the building makes an angle of 63.0

frez [133]

Since his line of sight 63 degrees makes with the tip of the building

Tan63° = height of building / Horizontal distance

tan63° = Height / 50

50tan63° = Height

Height = 50tan63°

Height ≈ 50*1.9626

Height ≈ 98.13 m

Height of the building is ≈ 98.13 m. Mind you in solving for this height we have neglected the height of Daniel.

The height of building actually should be 98.13 m plus the height of Daniel. Since the 63° was measured from his eye level.

4 0

2 years ago

A carmaker has designed a car that can reach a maximum acceleration of 12 meters/second2. The car’s mass is 1,515 kilograms. Ass

Vlada [557]

1) 15 / 12 = 1.25 ratio
2) to increase acceleration 1.25 times (with same F, or same engine) you have to lower mass 1.25 times
3) 1515/1.25 = 1212 kg

choose A

6 0

2 years ago

The magnetic field around the head has been measured to be approximately 3.00×10−8 gauss . Although the currents that cause this

konstantin123 [22]

Answer:

$3.81972\times 10^{-7}\ A$

Explanation:

B = Magnetic field = $3\times 10^{-8}\ G$

d = Diameter of loop = 16 cm

r = Radius = $\frac{d}{2}=\frac{16}{2}=8\ cm$

i = Current

$\mu_0$ = Vacuum permeability = $4\pi \times 10^{-7}\ H/m$

The magnetic field of a loop is given by

$B=\frac{\mu_0i}{2r}\\\Rightarrow i=\frac{B2r}{\mu_0}\\\Rightarrow i=\frac{3\times 10^{-8}\times 10^{-4}\times 2\times 0.08}{4\pi\times 10^{-7}}\\\Rightarrow i=3.81972\times 10^{-7}\ A$

The current needed to produce such a field at the center of the loop is $3.81972\times 10^{-7}\ A$

5 0

2 years ago

From the edge of a roof you throw a snowball downward that strikes the ground with 100J of kinetic energy. then you throw a seco

Vanyuwa [196]

Answer:

The second snowball hits the ground with a kinetic energy of 100 Joules

Explanation:

Given that,

From the edge of a roof you throw a snowball downward that strikes the ground with 100 J of kinetic energy. It is a case of conservation of energy.

At the highest point,

$mgh+\dfrac{1}{2}mu^2=mgh'+0$

$100=mgh'$

At lowest point,

$mgh'=K$

From above two equation, we get :

Kinetic energy, K = 100 J

So, the second snowball hits the ground with a kinetic energy of 100 Joules. So, the correct option is (A).

7 0

2 years ago