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AnnZ [28]
3 years ago
15

A student slides her 80.0-kg desk across the level floor of her dormitory room a distance 5.00 m at constant speed. If the coeff

icient of kinetic friction between the desk and the floor is 0.400, how much work did she do
Physics
1 answer:
katovenus [111]3 years ago
8 0

Answer:

1568 J

Explanation:

From the question given above, the following data were obtained:

Mass (m) = 80 Kg

Distance (d) = 5 m

Coefficient of kinetic friction (μ) = 0.4

Workdone (Wd) =?

Next, we shall determine the normal reaction. This can be obtained as follow:

Mass (m) = 80 Kg

Acceleration due to gravity (g) = 9.8 m/s²

Normal reaction (N) =?

N = mg

N = 80 × 9.8

N = 784 N

Next, we shall determine force of friction. This can be obtained as follow:

Coefficient of kinetic friction (μ) = 0.4

Normal reaction (N) = 784 N

Force of friction (F) =?

F = μN

F = 0.4 × 784

F = 313.6 N

Finally, we shall determine the work done. This can be obtained as follow:

Distance (d) = 5 m

Force of friction (F) = 313.6 N

Workdone (Wd) =?

Wd = F × d

Wd = 313.6 × 5

Wd = 1568 J

Thus, the workdone is 1568 J

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seropon [69]

Answer:

This came to mind

Explanation:

when a cannon fires (in real life or in the movies) have noticed that the cannon recoils, sliding backwards after the explosion. Again, a non-zero net force on the cannon changes its momentum.

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2 years ago
What happens to the bulb when the battery changes from 1.5V to 9v?
timofeeve [1]

Answer:

it gets brighter because the volta increases

4 0
3 years ago
Three identical resistors are connected in parallel to a battery. If the current of 12. A flows from the battery, how much curre
Doss [256]

Answer:

4 A

Explanation:

We are given that

R_1=R_2=R_3=4\Omega

I=12 A

We have to find the current flowing through each resistor.

We know that in parallel combination current flowing through different resistors are different and potential difference across each resistor is same.

Formula :

\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}

Using the formula

\frac{1}{R}=\frac{1}{4}+\frac{1}{4}+\frac{1}{4}=\frac{3}{4}

R=\frac{4}{3}\Omega

V=IR

Substitute the values

V=12\times \frac{4}{3}=16 V

I_1=\frac{V}{R_1}=\frac{16}{4}=4 A

I_1=I_2=I_3=4 A

Hence, current flows through any one of the resistors is 4 A.

7 0
3 years ago
You set your stationary bike on a high 80-N friction-like resistive force and cycle for 30 min at a speed of 8.0 m/s . Your body
stellarik [79]

A) The change in internal chemical energy is 1.15\cdot 10^7 J

B) The time needed is 1 minute

Explanation:

First of all, we start by calculating the power output of you and the bike, given by:

P=Fv

where

F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed

v = 8.0 m/s is the velocity

Substituting,

P=(80)(8.0)=640 W

The energy output is related to the power by the equation

P=\frac{E}{t}

where:

P = 640 W is the power output

E is the energy output

t = 30 min \cdot 60 = 1800 s is the time elapsed

Solving for E,

E=Pt=(640)(1800)=1.15\cdot 10^6 J

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

\Delta E = \frac{E}{0.10}=\frac{1.15\cdot 10^6}{0.10}=1.15\cdot 10^7 J

B)

From the previous part, we found that in a time of

t = 30 min

the amount of internal chemical energy converted is

E=1.15\cdot 10^7 J

Here we want to find the time t' needed to convert an amount of chemical energy of

E'=3.8\cdot 10^5 J

So we can setup the following proportion:

\frac{t}{E}=\frac{t'}{E'}

And solving for t',

t'=\frac{E't}{E}=\frac{(3.8\cdot 10^5)(30)}{1.15\cdot 10^7}=1 min

Learn more about power and energy:

brainly.com/question/7956557

#LearnwithBrainly

3 0
3 years ago
Whats the difference between speed and velocity of an object
ss7ja [257]
The difference between speed and velocity is that the speed is a scalar quantity which means that you can say that this object has a speed of x m/s but you don't have to define its direction
while the velocity is a vector quantity which means that you have to express the velocity by which it moves in x,y and z directions and its norm is the speed
4 0
3 years ago
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