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3 years ago

If a girl carries groceries up a flight of stairs, is she doing work on the groceries? Explain.

Physics

1 answer:

nikdorinn [45]3 years ago

4 0

Answer:

Explanation:

Yes she is doing work. With or without the groceries, she is still doing work. She does more work with the groceries than without because Work is defined by F which is defined by mass. The mass increases with the groceries.

The work done is against the force of gravity.

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An 92-kg football player traveling 5.0m/s in stopped in 10s by a tackler. What is the original kinetic energy of the player? Exp

Artemon [7]

Explanation:

It is given that,

Mass of the football player, m = 92 kg

Velocity of player, v = 5 m/s

Time taken, t = 10 s

(1) We need to find the original kinetic energy of the player. It is given by :

$k=\dfrac{1}{2}mv^2$

$k=\dfrac{1}{2}\times (92\ kg)\times (5\ m/s)^2$

k = 1150 J

In two significant figure, $k=1.2\times 10^3\ J$

(2) We know that work done is equal to the change in kinetic energy. Work done per unit time is called power of the player. We need to find the average power required to stop him. So, his final velocity v = 0

i.e. $P=\dfrac{W}{t}=\dfrac{\Delta K}{t}$

$P=\dfrac{\dfrac{1}{2}\times (92\ kg)\times (5\ m/s)^2}{10\ s}$

P = 115 watts

In two significant figures, $P=1.2\times 10^2\ Watts$

Hence, this is the required solution.

6 0

3 years ago

Jane has a mass of 55 kg and his body covers 700 nails with a surface area of 1.00 mm,

Oksana_A [137]

We have,

Jane mass is 55 kg
His body covered with 700 nails all of them having a surface area of 1.00 mm² each = 700 × 1 = 700 mm² = 700/1000000 = 7/10000

We know that,

Pressure = Force/Area

Let's calculate force as we already have area;

F = ma
F = 55 × 9.8 { Acceleration due to gravity }
F = 539 N

Now, if should she would be on 700 nails then pressure will be;

P = F/A
P = 539/7 × 10000
P = 5390000/7
P = 770,000 Pascal

And if should would be on a 1 nail only,

P = F/A
P = 539/1 × 1000000
P = 539000000 Pascal

As, you can notice yourself that the pressure will be so high with only 1 nail and because of this, nail will pass through jane's body.

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3 years ago

What are close-toed shoes least likely to provide protection against?

Dennis_Churaev [7]

Hydrogen gas is harmless to your feet so since you don’t need protection against it that seems the best answer.

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The wetter the surface, the friction

allochka39001 [22]

Answer: Water can either increase or decrease the friction between surfaces.

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3 years ago

Which occurs when a wave is reflected?

dmitriy555 [2]

Answer: The wave can flip upside down.

Reflection is the bending of a wave when it cannot pass through. For example, plain mirrors which are flat, a ray of light hits the mirror and is reflected from the mirror since it cannot pass through

When reflection occurs the speed and frequency of the wave does not change but the wave is flipped upside down.

The speed does not change because speed is affected by the change in medium the frequency also remains the same since the energy of the wave does not change.

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If a girl carries groceries up a flight of stairs, is she doing work on the groceries? Explain.​

If a girl carries groceries up a flight of stairs, is she doing work on the groceries? Explain.