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3 years ago

10

Starting from rest, a 88-kg firefighter slides down a fire pole. The average frictional force exerted on him by the pole has a m

agnitude of 800 N, and his speed at the bottom of the pole is 3.2 m/s. How far did he slide down the pole?

1 answer:

Cloud [144]3 years ago

3 0

Answer:h=7.22 m

Explanation:

Given

mass of firefighter $m=88 kg$

Frictional Force $F=800 N$

average speed at bottom $v=3.2 m/s$

Let h be the height of Pole

net force on Firefighter is

$F_{net}=88\times 9.8-800=62.4$

therefore net acceleration is

$a_{net}=\frac{62.4}{88}=0.709 m/s^2$

using $v^2-u^2=2ah$

here $v=3.2 m/s$

$u=0$

$(3.2)^2-0=2\times 0.709\times h$

$h=\frac{10.24}{1.418}$

$h=7.22 m$

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We can calculate this with the law of conservation of energy. Here we have a food package with a mass m=40 kg, that is in the height h=500 m and all of it's energy is potential. When it is dropped, it's potential energy gets converted into kinetic energy. So we can say that its kinetic and potential energy are equal, because we are neglecting air resistance:

Ek=Ep, where Ek=(1/2)*m*v² and Ep=m*g*h, where m is the mass of the body, g=9.81 m/s² and h is the height of the body.

(1/2)*m*v²=m*g*h, masses cancel out and we get:

(1/2)*v²=g*h, and we multiply by 2 both sides of the equation

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So the package is moving with the speed of v= 99.04 m/s when it hits the ground.

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2 years ago

A cylinder which is in a horizontal position contains an unknown noble gas at 4.63 × 104 Pa and is sealed with a massless piston

AleksandrR [38]

Answer:

The change in internal energy of the system is -17746.78 J

Explanation:

Given that,

Pressure $P=4.63\times10^{4}\ Pa$

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Using thermodynamics first equation

$dU=Q-W$ ...(I)

Where, dU = internal energy

Q = heat

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Put the value of W in equation (I)

$dU=Q-PdV$

Where, W = PdV

Put the value in the equation

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3 years ago

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Answer:

96 Joules

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3 years ago

What is the resistance of a carbon rod at 25.8 ∘C if its resistance is 0.0200 Ω at 0.0 ∘C ?

torisob [31]

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<h3 /><h3>What is a resistor?</h3>

A resistor is an electrical component that controls or restricts how much electrical current can pass across a circuit in an electronic device. A specified voltage can be supplied via resistors to an active device like a transistor.

The temperature of the resistor varies based on the variation in the temperature. The equation that describes the relationship between the two of them is:

R = R0[1+ alpha(T-T0)] where:

R is the new resistance we are looking for

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R0 is the resistance at T0 = 0.0200 ohms

T is the temperature at which we want to get R = 0

Substitute in the equation to get R as follows:

R = 0.0200 [1+( ₋ 4.8 x $10^{-4}$ ) (0-25.8)] = 0.02020 ohm

To know more about resistance refer to: brainly.com/question/11431009

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1 year ago

A spherical drop of water carrying a charge of 42 pC has a potential of 620 V at its surface (with V = 0 at infinity). (a) What

iren [92.7K]

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