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A ball is dropped from a height of 20m and renounce with the velocity which is 3/4 of d velocity with which it hits the ground.

Mashutka [201]

Answer:

1.73 seconds

Explanation:

The velocity the ball first hits the ground with is:

v² = v₀² + 2aΔx

v² = (0 m/s)² + 2 (-10 m/s²) (-20 m)

v = -20 m/s

The velocity it rebounds with is 3/4 of that in the opposite direction, or 15 m/s.

The time it takes to return to the ground is:

Δx = v₀ t + ½ at²

0 = (15 m/s) t + ½ (-10 m/s²) t²

0 = t (15 − 5t²)

t = √3

t ≈ 1.73 seconds

3 0

3 years ago

An astronaut weighs 8.00 × 102 newtons on the sur- face of Earth. What is the weight of the astronaut 6.37 × 106 meters above th

kolbaska11 [484]

Answer:

$mg=200.4 N$ .

Explanation:

This problem can be solved using Newton's law of universal gravitation: $F=G\frac{m_{1}m_{2}}{r^{2}}$ ,

where F is the gravitational force between two masses $m_{1}$ and $m_{2}$ , $r$ is the distance between the masses (their center of mass), and $G=6.674*10^{-11}(m^{3}kg^{-1}s^{-2})$ is the gravitational constant.

We know the weight of the astronout on the surface, with this we can find his mass. Letting $w_{s}$ be the weight on the surface:

$w_{s}=mg$ ,

$mg=8*10^{2}$ ,

$m=(8*10^{2})/g$ ,

since we now that $g=9.8m/s^{2}$ we get that the mass is

$m=81.6kg$ .

Now we can use Newton's law of universal gravitation

$F=G\frac{Mm}{r^{2}}$ ,

where $m$ is the mass of the astronaut and $M$ is the mass of the earth. From Newton's second law we know that

$F=ma$ ,

in this case the acceleration is the gravity so

$F=mg$ , (<u>becarefull, gravity at this point is no longer</u> $9.8m/s^{2}$ <u>because we are not in the surface anymore</u>)

and this get us to

$mg=G\frac{Mm}{r^{2}}$ , where $mg$ is his new weight.

We need to remember that the mass of the earth is $M=5.972*10^{24}kg$ and its radius is $6.37*10^{6}m$ .

The total distance between the astronaut and the earth is

$r=(6.37*10^{6}+6.37*10^{6})=2(6.37*10^{6})=12.74*10^{6}$ meters.

Now we can compute his weigh:

$mg=G\frac{Mm}{r^{2}}$ ,

$mg=(6.674*10^{-11})\frac{(5.972*10^{24})(81.6)}{(12.74*10^{6})^{2}}$ ,

$mg=200.4 N$ .

5 0

3 years ago

What type of data do scientists use to predict tornadoes?

Sav [38]

Correct answer would be d

5 0

3 years ago

Car wheel's slip in mud. why?

Lina20 [59]

Answer:

Because its wet

Explanation:

3 0

4 years ago

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A beaker of water is heated to increase its solubility, and it is saturated with a solid solute compound, such as salt. Then the

Nimfa-mama [501]

Answer:

The solid crystal will precipitate.

Explanation:

Solubility indicates how much solid can be in solution without it precipitating and depends on the temperature for most salts or compounds, increasing as the temperature rises.

Therefore, if the beaker is heated, more solid will remain in solution, in this case until saturation (the maximum amount of the solid that can be in solution without it precipitating).

As the temperature drops, the solubility drops, therefore any amount of solid that is added additionally will precipitate.

5 0

3 years ago

Read 2 more answers