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3 years ago

6. A 2.2 kg rock rests on the edge of a bridge that is 3.3 m above a river. What is the

Physics

1 answer:

vovikov84 [41]3 years ago

6 0

Answer: 71 J

Explanation: The formula for gravitational potential energy is Epg= mgh.

So you plug in 2.2 as m, 3.3 as h and 9.81 as g. Once you do that you should get an answer of 71.2206. But because there are only two significant digits in the question, your answer must also have two significant digits.

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The Moon takes about 27 days to orbit the Earth. Assuming a circular orbit, how fast is it orbiting? Express your answer in km/h

Vinvika [58]

Answer:

3727.24km/h

Explanation:

Hello!

To solve this problem we must first know what is the distance from the earth to the moon, this will be our radius.

=384400Km

Then we find the distance traveled which would be the perimeter of a circle = 2πr, finally to find the speed we divide the distance traveled by 27 days.

Finally we use conversion factor to have the speed in km / h

solving

$perimeter= 2(3.14)r=2(3.14)(384400Km)=2415256.432km\\Speed=\frac{2415256.432km}{27days} *\frac{1day}{24h} =3727.24km/h$

the moon is orbiting at speed of 3727.24km/h

7 0

3 years ago

If a bus is running with a speed of 72 km/hr,calculate the distance travelled by it in 5 second.Which of the following is right

ratelena [41]

Answer:

100m

Explanation:

conversation km to meter

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7 0

2 years ago

What happens to the volume of a loaf of bread that is squeezed? The mass? The density?

nalin [4]

Explanation:

The volume of the bread decreases, making the bread appear more compact, and smaller in size. The mass stays the same, it won't change unless part of the bread is removed. The density increases, the air bubbles inside of the bread get squished down, causing the bread to be smaller, and in turn, causing it to be more solid.

I hope this helped!

Thanks!

Your friend in answering,

~Steve

3 0

2 years ago

vA 61.2-kg circus performer is fired from a cannon that is elevated at an angle of 57.8 ° above the horizontal. The cannon uses

dsp73

Answer:

The effective spring constant of the firing mechanism is 1808N/m.

Explanation:

First, we can use kinematics to obtain the initial velocity of the performer. Since we know the angle at which he was launched, the horizontal distance and the time in which it's traveled, we can calculate the speed by:

$v_0_x=\frac{x}{t}\\ \\v_0\cos\theta=\frac{x}{t}\\\\v_0=\frac{x}{t\cos\theta}$

(This is correct because the horizontal motion has acceleration zero). Then:

$v_0=\frac{20.8m}{(2.60s)\cos57.8\°}\\\\v_0=15.0m/s$

Now, we can use energy to obtain the spring constant of the firing mechanism. By the conservation of mechanical energy, considering the instant in which the elastic band is at its maximum stretch as t=0, and the instant in which the performer flies free of the bands as final time, we have:

$E_0=E_f\\\\U_e=K\\\\\frac{1}{2}kx^2=\frac{1}{2}mv^2\\\\\implies k=\frac{mv^2}{x^2}$