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3 years ago

1) Which of the following explains why a bicycle uses a gear?

2 answers:

7 0

1. "The gear decreases effort force" is the one among the following choices given in the question that <span>explains why a bicycle uses a gear. The correct option among all the options is option "C".

2. A can opener is a compound machine. The correct option among all the options that are given in the question is the second option or option "B".</span>

Marta_Voda [28]3 years ago

4 0

Answer:

1) D. The gear decreases resistance force

2) B. A car opener

Explanation:

1): A bicycle uses a gear to decrease the resistance force as when the gears are shifted, the chain moves from a larger ring to a smaller one thus reducing the surface area of the ring as well as friction which results into a greater speed by applying same amount of effort.

2): As a compound machine is a combination of more than one simple machine. Out of all the options, a car opener is said to be a compound machine as it consist of a lever, screw, wedge and axle and wheel.

These are some of the simple machines which combines to make a complex machine ( car opener ).

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You are moving into an apartment and take the elevator to the 6th floor. Suppose your weight is 660 N and that of your belonging

Ivan

Answer:

Explanation:

Total weight

My weight+weight of belongings

660+1100=1760N.

a. Work done by the elevator to travel a total height of 15.2m

Using newton law of motion

ΣF = ma

There are only two forces acting upward, the weight and the reaction by the elevator

Also note it is moving at constant velocity then, a=0

N - W=0

Then, N=W

N=1760N

So, workdone is given as

Wordone, =force × distance

Work done=1760×15.2

W=26,752J

W=26.752KJ

b. Work done on me alone is still need to go through the same process but will remove the weight of the belonging

Therefore,

Weight now = 660N

And using the same equation of motion

ΣF = ma

Comstant velocity, a=0

N - W=0

N=W

N=660N

Then, workdone

W=F×d

W=660×15.2

W=10,032J

W=10.032KJ

6 0

4 years ago

Read 2 more answers

There are 152 steps between the ground floor and the sixth floor in a building. Each step is 16.2 cm tall. It takes 3 minutes an

lisabon 2012 [21]

Answer:

14.4kJ

Explanation:

Work = Force x distance

W × h = mgh

Given that,

mass m, = 59.5kg

acceleration due to gravity = 9.8m/s^2

height ,h = 16.2cm

convert to m is 0.162m

How much work = m x g x h

height is 0.162 x 152 steps

h = 24.624m

work = 59.5 x 9.8 x 24.624

= 14,358.25Joule

= 14.4kJ

7 0

3 years ago

Two golf balls are thrown with the same speed off the top of a large bridge at the same time. ball a is thrown straight downward

iren2701 [21]

I think that ball a hit the ground because it says that it went straight down.

8 0

4 years ago

Discuss five occasions when people dance

Xelga [282]

Answer:

Party, Birthday, Weddings, Nightclub, Just for fun

7 0

3 years ago

series RC circuit is built with a 15 kΩ resistor and a parallel-plate capacitor with 18-cm-diameter electrodes. A 18 V, 36 kHz s

andre [41]

Answer:

$d=1.84\ mm$

Explanation:

<u>Capacitance</u>

A two parallel-plate capacitor has a capacitance of

$\displaystyle C=\frac{\epsilon_o A}{d}$

where

$\epsilon_o=8.85\cdot 10^{-12}\ F/m$

A = area of the plates = $\pi r^2$

d = separation of the plates

$\displaystyle d=\frac{\epsilon_o A}{C}=\frac{\epsilon_o \pi r^2}{C}$

We need to compute C. We'll use the circuit parameters for that. The reactance of a capacitor is given by

$\displaystyle X_c=\frac{1}{wC}$

where w is the angular frequency

$w=2\pi f=2\pi \cdot 36000=226194.67\ rad/s$

Solving for C

$\displaystyle C=\frac{1}{wX_c}$

The reactance can be found knowing the total impedance of the circuit:

$Z^2=R^2+X_c^2$

Where R is the resistance, $R=15 K\Omega=15000\Omega$ . Solving for Xc

$X_c^2=Z^2-R^2$

The magnitude of the impedance is computed as the ratio of the rms voltage and rms current

$\displaystyle Z=\frac{V}{I}$

The rms current is the peak current Ip divided by $\sqrt{2}$ , thus

$\displaystyle Z=\frac{\sqrt{2}V}{I_p}$

$I_p=0.65\ mA/1000=0.00065\ A$

Now collect formulas

$\displaystyle X_c^2=Z^2-R^2=\left(\frac{\sqrt{2}V}{I_p}\right)^2-R^2$

Or, equivalently

$\displaystyle X_c=\sqrt{\frac{2V^2}{I_p^2}-R^2}$

$\displaystyle X_c=\sqrt{\frac{2\cdot 18^2}{0.00065^2}-15000^2}$

$X_c=36176.34\ \Omega$

The capacitance is now

$\displaystyle C=\frac{1}{226194.67\cdot 36176.34}=1.22\cdot 10^{-10}\ F$

The radius of the plates is

$r=18\ cm/2=9 \ cm = 0.09 \ m$

The separation between the plates is

$\displaystyle d=\frac{8.85\cdot 10^{-12} \cdot \pi\cdot 0.09^2}{1.22\cdot 10^{-10}}$

$d=0.00184\ m$

$\boxed{d=1.84\ mm}$

8 0

3 years ago