Ask question

Ask question

All categories

3 years ago

11

ANSWER THE FOLLOWING QUESTION AND MAKE SURE TO GIVE A FULL DESCRIPTION TO HOW YOU GOT YOUR ANSWER (EX. make sure to use blank ru

le in order to get blank answer) URGENT
A car of mass 1800 kg moving with a speed at 90 km/hr is brought to rest by the application of disc brakes. Find the average increase in temperature if the brakes if each of the four brakes has a mass of 4.5 kg. Take the specific heat capacity of the brake material to be 680 J/kg degree C, and assume that all the kinetic energy, 562.5 kJ, is changed into heat energy in the brakes.

1 answer:

vazorg [7]3 years ago

6 0

Here is how I did it

You might be interested in

Identify two structural characteristics specific to muscle tissue.

Semmy [17]

Answer:

Explanation:

Muscle cells are excitable; they respond to a stimulus.meaning they can shorten and generate a pulling force. When attached between two movable objects, such as two bones, contraction of the muscles cause the bones to move.It contains protein fibers which contract to make the cell shorter.

7 0

2 years ago

Read 2 more answers

A 3.5 kilogram object is swung in a circular path on the end of a 0.4 meter long string. the object makes one trip around the ci

jeyben [28]

Path length is 2*pi*0.4=2.512
Speed=distance/time
Speed =2.512/0.2=12.56m/s

6 0

3 years ago

A mole of ideal gas expands at T=27 °C. The pressure changes from 20 atm to 1 atm. What’s the work that the gas has done and wha

Airida [17]

Answer:

The work made by the gas is 7475.69 joules
The heat absorbed is 7475.69 joules

Explanation:

<h3>Work</h3>

We know that the differential work made by the gas its defined as:

$dW = P \ dv$

We can solve this by integration:

$\Delta W = \int\limits_{s_1}^{s_2}\,dW = \int\limits_{v_1}^{v_2} P \ dv$

but, first, we need to find the dependence of Pressure with Volume. For this, we can use the ideal gas law

$P \ V = \ n \ R \ T$

$P = \frac{\ n \ R \ T}{V}$

This give us

$\int\limits_{v_1}^{v_2} P \ dv = \int\limits_{v_1}^{v_2} \frac{\ n \ R \ T}{V} \ dv$

As n, R and T are constants

$\int\limits_{v_1}^{v_2} P \ dv = \ n \ R \ T \int\limits_{v_1}^{v_2} \frac{1}{V} \ dv$

$\Delta W= \ n \ R \ T \left [ ln (V) \right ]^{v_2}_{v_1}$

$\Delta W = \ n \ R \ T ( ln (v_2) - ln (v_1 )$

$\Delta W = \ n \ R \ T ( ln (v_2) - ln (v_1 )$

$\Delta W = \ n \ R \ T ln (\frac{v_2}{v_1})$

But the volume is:

$V = \frac{\ n \ R \ T}{P}$

$\Delta W = \ n \ R \ T ln(\frac{\frac{\ n \ R \ T}{P_2}}{\frac{\ n \ R \ T}{P_1}} )$

$\Delta W = \ n \ R \ T ln(\frac{P_1}{P_2})$

Now, lets use the value from the problem.

The temperature its:

$T = 27 \° C = 300.15 \ K$

The ideal gas constant:

$R = 8.314 \frac{m^3 \ Pa}{K \ mol}$

So:

$\Delta W = \ 1 mol \ 8.314 \frac{m^3 \ Pa}{K \ mol} \ 300.15 \ K ln (\frac{20 atm}{1 atm})$

$\Delta W = 7475.69 joules$

<h3>Heat</h3>

We know that, for an ideal gas, the energy is:

$E= c_v n R T$

where $c_v$ its the internal energy of the gas. As the temperature its constant, we know that the gas must have the energy is constant.

By the first law of thermodynamics, we know

$\Delta E = \Delta Q - \Delta W$

where $\Delta W$ is the Work made by the gas (please, be careful with this sign convention, its not always the same.)

So:

$\Delta E = 0$

$\Delta Q = \Delta W$

7 0

2 years ago

BRAINLEST FOR CORRECT ANSWER

xxMikexx [17]

Answer:

3kg sledgehammer swung at 1.5 m/s

Explanation:

Small Sledgehammer:

Mass:3.0

Velocity:1.5

MASS×VELOCITY=MOMENTUM

3.0×1.5= 4.5 (momentum)

Large Sledgehammer:

Mass:4.0

Velocity:0.9

4.0×0.9=3.6 (momentum)

higher momentum is the smaller Sledgehammer.

3 0

3 years ago

An airplane cruises at 900 km/h relative to the air. It is flying from Denver, Colorado, due west to Reno, Nevada, a distance of

Ulleksa [173]

Answer:

26.5 minutes

Explanation:

When the airplane is flying due West from Denver to Reno, the due-East wind with speed of 80km/h would reduce the ground speed by 80 km/h.

Its Denver to Reno ground speed is 900 - 80 = 720 km/h

The time it takes to cover 1200km at this speed is 1200 / 720 = 1.67 hours

On the other hand, when it returns from Reno to Denver in the due-East direction, the due-East wind with speed of 80km/h would add to the ground speed by 80 km/h

Its Reno to Denver ground speed is 900 + 80 = 980 km/h

The time it takes to cover 1200 km at this speed is 1200 / 980 = 1.22 hours

The difference it flight time would be 1.67 - 1.22 = 0.44 hours or 26.5 minutes

4 0

3 years ago