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3 years ago

2 A box of mass 3 kg is initially at rest. Find the kinetic energy acquired by the box if

Physics

1 answer:

bekas [8.4K]3 years ago

5 0

Answer: if 5N is applied for 5 seconds then it would move at a constant speed for one second then decrease in speed

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How long does it take lewis hamilton travelling at 156 mph to cover 16 miles?

Paladinen [302]

It takes him
t = 16 miles / 156 mph = 0.1 hours

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3 years ago

A 1.20-m cylindrical rod of diameter 0.570 cm is connected to a power supply that maintains a constant potential difference of 1

nasty-shy [4]

(a) $1.72\cdot 10^{-5} \Omega m$

The resistance of the rod is given by:

$R=\rho \frac{L}{A}$ (1)

where

$\rho$ is the material resistivity

L = 1.20 m is the length of the rod

A is the cross-sectional area

The radius of the rod is half the diameter: $r=0.570 cm/2=0.285 cm=2.85\cdot 10^{-3} m$ , so the cross-sectional area is

$A=\pi r^2=\pi (2.85\cdot 10^{-3} m)^2=2.55\cdot 10^{-5} m^2$

The resistance at 20°C can be found by using Ohm's law. In fact, we know:

- The voltage at this temperature is V = 15.0 V

- The current at this temperature is I = 18.6 A

So, the resistance is

$R=\frac{V}{I}=\frac{15.0 V}{18.6 A}=0.81 \Omega$

And now we can re-arrange the eq.(1) to solve for the resistivity:

$\rho=\frac{RA}{L}=\frac{(0.81 \Omega)(2.55\cdot 10^{-5} m^2)}{1.20 m}=1.72\cdot 10^{-5} \Omega m$

(b) $8.57\cdot 10^{-4} /{\circ}C$

First of all, let's find the new resistance of the wire at 92.0°C. In this case, the current is

I = 17.5 A

So the resistance is

$R=\frac{V}{I}=\frac{15.0 V}{17.5 A}=0.86 \Omega$

The equation that gives the change in resistance as a function of the temperature is

$R(T)=R_0 (1+\alpha(T-T_0))$

where

$R(T)=0.86 \Omega$ is the resistance at the new temperature (92.0°C)

$R_0=0.81 \Omega$ is the resistance at the original temperature (20.0°C)

$\alpha$ is the temperature coefficient of resistivity

$T=92^{\circ}C$

$T_0 = 20^{\circ}$

Solving the formula for $\alpha$ , we find

$\alpha=\frac{\frac{R(T)}{R_0}-1}{T-T_0}=\frac{\frac{0.86 \Omega}{0.81 \Omega}-1}{92C-20C}=8.57\cdot 10^{-4} /{\circ}C$

5 0

3 years ago

What will happen to the Sun after it loses so much mass that its gravity

Natali5045456 [20]

Answer:

The answer is C

Explanation:

7 0

2 years ago

Read 2 more answers

The substances referenced in the table are being considered for use in cooking materials. Since the materials must be melted dur

frutty [35]

Brass requires more energy than silver

Aluminum requires more energy than copper

Aluminum requires more energy than brass

Explanation:

The specific heat capacity of a substance indicates the amount of heat energy required to raise 1 kg of that substance by 1 degree in temperature.

Mathematically:

$C=\frac{Q}{m\Delta T}$

where

Q is the heat supplied to the substance

m is the mass of the substance

$\Delta T$ is the change in temperature

Therefore, the higher the specific heat capacity of a substance, the more energy is needed to increase its temperature.

Here we can compare the specific heat capacity of the materials mentioned:

Silver: $C=0.233 J/gK$

Brass: $C=0.380 J/gK$

Platinum: $C=0.130 J/gK$

Aluminium: $C=0.910 J/gK$

Copper: $C=0.390 J/gK$

Therefore, the correct statements are:

Brass requires more energy than silver

Aluminum requires more energy than copper

Aluminum requires more energy than brass

Learn more about specific heat:

brainly.com/question/3032746

brainly.com/question/4759369

#LearnwithBrainly

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3 years ago

In the 1920s what did Edmund hubble notice about the galaxies

zlopas [31]

Hubble noticed that the galaxies were moving away from us, which meant the universe was expanding.

This is why constellations change over time. In some years, the Big Dipper won't actually look like a dipper anymore.

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3 years ago