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3 years ago

7

A boy is running with a kinetic energy of 82"" j if the boy has a mass of 80 kg what is his speed

1 answer:

weqwewe [10]3 years ago

4 0

Explanation:

$v = \sqrt \ \frac{ke}{ \frac{1}{2} m}$

$v = \sqrt \ \frac{82}{ \frac{1}{2} (80)}$

v = 1.4317821063276 m/s

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A kid applies a force of 70 N to a ball over 1.1 meters. How much work did he do on the ball?

LekaFEV [45]

Answer:

77J

Explanation:

Not really an explanation to this, I just had this lesson last year and remembered it.

Hope I helped! ☺

8 0

3 years ago

Say that you are in a large room at temperature TC = 300 K. Someone gives you a pot of hot soup at a temperature of TH = 340 K.

DiKsa [7]

Answer:0.061

Explanation:

Given

$T_C=300 k$

Temperature of soup $T_H=340 K$

heat capacity of soup $c_v=33 J/K$

Here Temperature of soup is constantly decreasing

suppose T is the temperature of soup at any instant

efficiency is given by

$\eta =\frac{dW}{Q}=1-\frac{T_C}{T}$

$dW=Q(1-\frac{T_C}{T})$

$dW=c_v(1-\frac{T_C}{T})dT$

integrating From $T_H$ to $T_C$

$\int dW=\int_{T_C}^{T_H}c_v(1-\frac{T_C}{T})dT$

$W=\int_{T_C}^{T_H}33\cdot (1-\frac{300}{T})dT$

$W=c_v\left [ T-T_C\ln T\right ]_{T_H}^{T_C}$

$W=c_v\left [ \left ( T_C-T_H\right )-T_C\left ( \ln \frac{T_C}{T_H}\right )\right ]$

Now heat lost by soup is given by

$Q=c_v(T_C-T_H)$

Fraction of the total heat that is lost by the soup can be turned is given by

$=\frac{W}{Q}$

$=\frac{c_v\left [ \left ( T_C-T_H\right )-T_C\left ( \ln \frac{T_C}{T_H}\right )\right ]}{c_v(T_C-T_H)}$

$=\frac{T_C-T_H-T_C\ln (\frac{T_C}{T_H})}{T_C-T_H}$

$=\frac{300-340-300\ln (\frac{300}{340})}{300-340}$

$=\frac{-40+37.548}{-40}$

$=0.061$

4 0

3 years ago

A sample of 5.6 L of a gas is at a pressure of 1.5 atm. If the volume of the gas is compressed to 4.8 L, what will the new press

Effectus [21]

Answer:

1.75atm

Explanation:

According to Boyle's law, the pressure P of a fixed mass of gas is inversely proportional to it's volume V provided that the temperature remains constant.

$P\alpha \frac{1}{V}\\hence\\PV=constant$

This implies the following;

$P_1V_1=P_2V_2=...=P_nV_n............(1)$ Provided temperature is kept constant.

Given;

$P_1=1.5atm\\V_1=5.6L\\P_2=?\\V_2=4.8L$

From equation (1), we can write;

$P_1V_1=P_2V_2\\hence\\1.5*5.6=P_2*4.8\\\\P_2=\frac{1.5*5.6}{4.8}\\\\P_2=1.75atm$

Since all the units are consistent, there is no need for conversion.

3 0

3 years ago

Read 2 more answers

17. (16 pts) You set up a two-slit experiment with a laser that produces light with a

Natali [406]

when the two waves interfere with eachother to make a dark spot the periodic difference of the two waves is π . the wave length for 2π is 600nm

. ie. for π difference it is 300nm

4 0

3 years ago

A 12 volt car battery is connected to a 3 ohm brake light. What is the current carrying energy to the lights?

zloy xaker [14]

Answer:

4 A

Explanation:

V = IR, where V=voltage, I=current, R=resistance. This is Ohm's Law. (remember that for units V = volts, Ω = ohms, A = amperes.)

V = IR

12 V = I * 3 Ω

12/3 = I

<u>I = 4 A</u>

8 0

3 years ago