You throw a rock out of a 7th story window. you time that it takes 3.7 seconds to hit the ground, and measure that it hit the ground 115 m from the base of the building? How fast must you have thrown the rock?
How high up must the 7th floor be?
If you had thrown it at the same speed but at the 28th floor, how far from the base of the building would it land?

Answers

Answer 1

Answer:

1) 31.1 m/s

The rock has been thrown straight out of the window: its motion on the horizontal direction is simply a uniform motion, with constant speed $v$ , because no forces act in the horizontal direction. The speed in a uniform motion is given by

$v=(S)/(t)$

where S is the distance traveled and t the time taken.

In this case, the distance by the rock before hitting the ground is $S=115 m$ and the time taken is $t=3.7 s$ , so the initial speed is given by

$v=(115 m)/(3.7 s)=31.1 m/s$

2) 67.1 m

In this part of the problem we are only interested in the vertical motion of the rock. The vertical motion is a uniformly accelerated motion, with constant acceleration $a=9.8 m/s^2$ (acceleration of gravity) towards the ground. In a uniformly accelerated motion, the distance traveled by the object is given by

$S=(1)/(2)at^2$

where t is the time. Substituting a=9.8 m/s^2 and t=3.7 s, we can find S, the vertical distance covered by the rock, which corresponds to the height of the 7th floor:

$S=(1)/(2)(9.8 m/s^2)(3.7 s)^2=67.1 m$

3) 230.1 m

The height of the 7th floor is 67.1 m. So we can assume that the height of each floor is

$h=(67.1 m)/(7)=9.6 m$

And so, the height of the 28th floor is

$h=28\cdot 9.6 m=268.8 m$

We can find the total time of the fall in this case by using the same formula of the previous part:

$S=(1)/(2)at^2$

In this case, S=268.8 m, so we can re-arrange the formula to find t

$t=\sqrt{(2S)/(g)}=\sqrt{(2(268.8 m))/(9.8 m/s^2)}=7.4 s$

And now we can consider the motion of the rock on the horizontal direction: we know that the rock travels at a constant speed of v=31.1 m/s, so the distance traveled is

$S=vt=(31.1 m/s)(7.4 s)=230.1 m$

And this is how far from the building the rock lands.

Answer 2

Answer: speed = distance/time taken
115/3.7 =31.08m/s^2

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Answers

The white fur reflects all colors, so would appear green.
The black fur reflects no colors, so would still appear black.

Answer:

Green and Black.

Explanation:

The white fur reflects all colors, so would appear green.

The black fur reflects no colors, so would still appear black.

If a step-up transformer has a primary coil with 15 turns, how many turns would be required in the secondary coil in order to increase the voltage from 80 volts to 160 volts? A. 8 turns B. 30 turns C. 80 turns D. 160 turns

Answers

Answer:

$N_2=30turns$

So option (b) will be correct option

Explanation:

We have given that there is a step up transformer in which number of turns in primary coil is 15

That is, $N_1=15$

Primary voltage $V_1=80volt$ , and secondary voltage $V_2=160volt$

We have to find the number of turns in the secondary \

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$(N_1)/(N_2)=(V_1)/(V_2)$

$(15)/(N_2)=(80)/(160)$

$N_2=30turns$

So option (b) will be correct option

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Answers

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Answers

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Answers

Answer:

It can hurt you if you get a carpet burn if you rub against carpet really fast and hard. It can help by keeping your shoes from slipping around all the time when you walk/run. Same with bike tires.

Explanation:

A chunk of aluminum at 91.4°C was added to 200.0 g of water at 15.5°C. The specific heat of aluminum is 0.897 J/g°C, and the specific heat of water is 4.18 J/g°C. When the temperature stabilized, the temperature of the mixture was 18.9°C. Assuming no heat was lost to the surroundings, what was the mass of aluminum added?

Answers

Final answer:

The mass of the aluminum added is calculated through the principle of conservation of energy, specifically thermal energy. By considering the heat lost by the aluminum and gained by the water, we can rearrange the equation for heat transfer and find that the mass of the aluminum is approximately 37.9 grams.

Explanation:

In this physics question, we're looking at a thermodynamic process involving a chunk of aluminum and water. Given the known values of their respective specific heats, the mass of water, and their final equilibrium temperature, we're aiming to find the mass of the aluminum.

We begin by understanding that in a closed system, the heat gained by one body is equal to the heat lost by another. In this case, the aluminum is losing heat, and the water is gaining it. The equation for heat transfer (Q = mcΔT), where m is mass, c is specific heat, and ΔT is change in temperature.

The heat gained by the water = mass of water * specific heat of water * change of temperature in water = 200g * 4.18J/g°C * (18.9°C - 15.5°C) = 2836.4J.

This is equal to the heat lost by the aluminum. Solving the analogous heat equation for the mass of the aluminum gives us the answer:

m = Q / (c * ΔT) = 2836.4J / (0.897J/g°C * (91.4°C - 18.9°C)) = 37.9g

So the mass of the aluminum is approximately 37.9 grams.

Learn more about Thermodynamics here:

brainly.com/question/35546325

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