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Mrac [35]
3 years ago
11

As a science project, you drop a watermelon off the top of the Empire State Building, 320 m above the sidewalk. It so happens th

at Superman flies by at the instant you release the watermelon. Superman is headed straight down with a speed of 39.0 m/s.
How fast is the watermelon going when it passes Superman?
Physics
1 answer:
SSSSS [86.1K]3 years ago
3 0

Answer:

The velocity of watermelon when it passes Superman is 78 m/s.

Explanation:

Height of the building, d = 320 m

Speed of the superman, v = 39 m/s

We need to find the speed of watermelon when it passes Superman. Let t is the time taken by the watermelon. So,

d=ut+\dfrac{1}{2}gt^2

Here u = 0

d=\dfrac{1}{2}gt^2

39t=\dfrac{1}{2}\times 9.8\times t^2

t = 7.95 seconds

Let v is the speed of the watermelon. It is given by :

v=gt

v=9.8\times 7.95

v = 77.91 m/s

or

v = 78 m/s

So, the velocity of watermelon when it passes Superman is 78 m/s.

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If the temperature of an iron sphere is increased A)its density will decrease .B)its volume will decrease. C)its mass will decre
babymother [125]

Answer:

A) Its density will decrease

Explanation:

When an object is heated, its volume increases. This is due to the fact that the particles in the medium vibrate more (if it is a solid) or they move more (if it is a liquid or a gas), therefore they tend to occupy a larger space.

At the same time, the mass of the object does not change, because the mass just represents the amount of matter contained in the object, so it does not increase/decrease at different temperatures.

The density of an object is defined as the ratio between the mass (m) and the volume (V):

d=\frac{m}{V}

We said that the mass remains unchanged while the volume increases: since the density is inversely proportional to the volume, this means that the density decreases.

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2 years ago
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A physicist drives through a stop light. When he is pulled over, he tells the police officer that the Doppler shift made the red
Alik [6]

Answer:

Speed of physicist car is 0.036c or 1.08 x 10⁷ m/s .

Explanation:

Doppler Effect is defined as the change in frequency or wavelength of the wave as the source or/and observer moving away or towards each other.

In this case, the Doppler effect equation in terms of wavelength is :

\lambda_{s} = \lambda_{o}\sqrt{\frac{1-\frac{v}{c} }{1+\frac{v}{c} } }       ......(1)

Here \lambda_{s} is source wavelength, \lambda_{o} is observed wavelength, v is speed of the observer and c is the speed of light.

Given :

Source wavelength, \lambda_{s} = 660 nm = 660 x 10⁻⁹ m

Observed wavelength, \lambda_{0} = 555 nm = 555 x 10⁻⁹ m

Substitute these values in the equation (1).

555\times10^{-9} } = 660\times10^{-9} \sqrt{\frac{1-\frac{v}{c} }{1+\frac{v}{c} } }

\sqrt{\frac{1-\frac{v}{c} }{1+\frac{v}{c} } } = 0.84

{\frac{1-\frac{v}{c} }{1+\frac{v}{c} } } = (0.84)^{2} = 0.7056

1-\frac{v}{c}=0.7056+0.7056\frac{v}{c}

\frac{v}{c}=\frac{0.2944}{8.056}

v = 0.036c=0.036\times3\times10^{8}

v = 1.08 x 10⁷ m/s  

8 0
3 years ago
While Bob is demonstrating the gravitational force on falling objects to his class, he drops an 1.0 lb bag of feathers from the
BartSMP [9]

In the experiment of free fall bob released a bag of mass 1 lb

so here we can say that initial speed of the bag is Zero

time taken by the bag to free fall is given as

t = 1.5 s

also the acceleration of free fall is given as

a = 9.8 m/s^2

now we will use kinematics equation here for finding the distance of free fall

d = v_i * t + \frac{1}{2} at^2

d = 0 + \frac{1}{2}*9.8* 1.5^2

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3 0
3 years ago
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andrey2020 [161]

Answer:

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Explanation:

The moment of inertia of the bodies can be calculated by the equation

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For bodies with symmetry this tabulated, the moment of inertia of the center of mass

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The parallel axes theorem allows us to calculate the moment of inertia with respect to different axes, without knowing the moment of inertia of the center of mass

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The sphere

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    D_{s} = 2,066 R

3 0
3 years ago
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