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2 years ago

Help with a length problem

Physics

2 answers:

Andru [333]2 years ago

6 0

It would be B

Explanation:
Because if you're not measuring in inches you want to go the next one down other than inches which would be millimeters!(: hope this helps.

Nat2105 [25]2 years ago

5 0

Answer:

B. Millimeters

Explanation:

Milliliters is a unit for volume

Millimeters are length, so its suitable for this.

Kilometers is also a unit used for length but its too big for a shoe measurement.

Kilograms is a unit for weight.

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The distiction between long and short term memory

RUDIKE [14]

Answer:

The main difference between short term and long term memory is that the short term memory stores data temporarily while the long term memory stores data permanently. Moreover, the short term memory is volatile while the long term memory is nonvolatile. Memory is the component in a computer that stores data and information.

Explanation:

4 0

2 years ago

A ball is dropped from rest from the top of a building of height h. At the same instant, a second ball is projected vertically u

uranmaximum [27]

Answer:

a) $t = \sqrt{\frac{h}{2g}}$

b) Ball 1 has a greater speed than ball 2 when they are passing.

c) The height is the same for both balls = 3h/4.

Explanation:

a) We can find the time when the two balls meet by equating the distances as follows:

$y = y_{0_{1}} + v_{0_{1}}t - \frac{1}{2}gt^{2}$

Where:

$y_{0_{1}}$ : is the initial height = h

$v_{0_{1}}$ : is the initial speed of ball 1 = 0 (it is dropped from rest)

$y = h - \frac{1}{2}gt^{2}$ (1)

Now, for ball 2 we have:

$y = y_{0_{2}} + v_{0_{2}}t - \frac{1}{2}gt^{2}$

Where:

$y_{0_{2}}$ : is the initial height of ball 2 = 0

$y = v_{0_{2}}t - \frac{1}{2}gt^{2}$ (2)

By equating equation (1) and (2) we have:

$h - \frac{1}{2}gt^{2} = v_{0_{2}}t - \frac{1}{2}gt^{2}$

$t=\frac{h}{v_{0_{2}}}$

Where the initial velocity of the ball 2 is:

$v_{f_{2}}^{2} = v_{0_{2}}^{2} - 2gh$

Since $v_{f_{2}}^{2}$ = 0 at the maximum height (h):

$v_{0_{2}} = \sqrt{2gh}$

Hence, the time when they pass each other is:

$t = \frac{h}{\sqrt{2gh}} = \sqrt{\frac{h}{2g}}$

b) When they are passing the speed of each one is:

For ball 1:

$v_{f_{1}} = - gt = -g*\sqrt{\frac{h}{2g}} = - 0.71\sqrt{gh}$

The minus sign is because ball 1 is going down.

For ball 2:

$v_{f_{2}} = v_{0_{2}} - gt = \sqrt{2gh} - g*\sqrt{\frac{h}{2g}} = (\sqrt{1} - \frac{1}{\sqrt{2}})*\sqrt{gh} = 0.41\sqrt{gh}$

Therefore, taking the magnitude of ball 1 we can see that it has a greater speed than ball 2 when they are passing.

c) The height of the ball is:

For ball 1:

$y_{1} = h - \frac{1}{2}gt^{2} = h - \frac{1}{2}g(\sqrt{\frac{h}{2g}})^{2} = \frac{3}{4}h$

For ball 2:

$y_{2} = v_{0_{2}}t - \frac{1}{2}gt^{2} = \sqrt{2gh}*\sqrt{\frac{h}{2g}} - \frac{1}{2}g(\sqrt{\frac{h}{2g}})^{2} = \frac{3}{4}h$

Then, when they are passing the height is the same for both = 3h/4.

I hope it helps you!

7 0

3 years ago

Comparing the speed of sound in liquids, gases, and solids, the speed of sound is usually lowest in ( ) and highest in ( ).

nydimaria [60]

Answer:

the answer is the 4th one. the speed of sound is lowest in gas and highest in solid and its because the molecules in solid is closer to each other than the molecules in gas and when the molecules are close to each other, they allow the waves of the sound to travel more quickly.

7 0

2 years ago

Which of these is always true about a real image?

hammer [34]

B. The image is always enlarged

6 0

2 years ago

A chemical reaction’s speed can be increased by ____.

fenix001 [56]

A. Using a catalyst

6 0

2 years ago

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