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2 years ago

A piece of toast weighing 8 grams is flying through the air at 15

Physics

1 answer:

Ket [755]2 years ago

6 0

The kinetic energy of toast is 0.06 J.

<u>Explanation:</u>

Kinetic energy is the way to determine the energy released when an object is in motion. In other times, it can be the energy required to move any object and to make it in motion.

As the mass of the toast is given as 8 g and speed is given as 15 m/s, if we ignore the friction caused by air molecules. Then the kinetic energy is the product of mass and square of velocity.

K.E. = $\frac{1}{2}$ × mass × v²

Kinetic energy = $\frac{1}{2} \times \frac{8}{1000} \times 15$

Since, the weight is given in grams , it needed to be converted into kg.

Kinetic energy = 0.06 J

Thus, the kinetic energy of toast is 0.06 J.

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A cat, walking along the window ledge of a new york apartment, knocks off a flower pot, which falls to the street 280 feet below

Harlamova29_29 [7]

H = 280 ft, the height of the flower pot.
g = 32 ft/s²

Neglect air resistance.
Note that 1 ft/s = 15/22 mi/h

The initial vertical velocity is zero.
Let v = the velocity with which the flower pot hits the ground.
Then
v² = 2gh
= 2*(32 ft/s²)*(280 ft)
= 17920 (ft/s)²
v = 133.866 ft/s

Also,
v = (133.866 ft/s)*(15/22 (mi/h)/(ft/s)) = 91.272 mi/h

Answer: 133.9 ft/s or 91.3 mi/h

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2 years ago

What quantity of heat must be removed from 20g<br>of water at 0°C to change it to ice at 0°C?

seraphim [82]

The quantity of heat must be removed is 1600 cal or 1,6 kcal.

<h3>Explanation : </h3>

From the question we will know if the condition of ice is at the latent point. So, the heat level not affect the temperature, but it can change the object existence. So, for the formula we can use.

$\boxed {\bold {Q = m \times L}}$

If :

Q = heat of latent (cal or J )
m = mass of the thing (g or kg)
L = latent coefficient (cal/g or J/kg)

<h3>Steps : </h3>

If :

m = mass of water = 20 g => its easier if we use kal/g°C
L = latent coefficient = 80 cal/g

Q = ... ?

Answer :

$Q = m \times L \\ Q = 20 \times 80 = 1600 \: cal$

So, the quantity of heat must be removed is 1600 cal or 1,6 kcal.

<u>Subject : Physics </u>

<u>Subject : Physics Keyword : Heat of latent</u>

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2 years ago

A net force of –8750N is used to stop of 1250.kg car travelling 25m/s. What braking distance is needed to bring the car to a hal

Karolina [17]

Answer:

d = 44.64 m

Explanation:

Given that,

Net force acting on the car, F = -8750 N

The mass of the car, m = 1250 kg

Initial speed of the car, u = 25 m/s

Final speed, v = 0 (it stops)

The formula for the net force is :

F = ma

a is acceleration of the car

$a=\dfrac{F}{m}\\\\a=\dfrac{-8750}{1250}\\\\a=-7\ m/s^2$

Let d be the breaking distance. It can be calculated using third equation of motion as :

$v^2-u^2=2ad\\\\d=\dfrac{v^2-u^2}{2a}\\\\d=\dfrac{0^2-(25)^2}{2\times (-7)}\\\\d=44.64\ m$

So, the required distance covered by the car is 44.64 m.

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2 years ago

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astraxan [27]

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