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3 years ago

Which statement correctly applies to a spinning mobile that changes its velocity over a period of time?

Physics

1 answer:

qaws [65]3 years ago

3 0

Answer: D

Explanation:

First, we know that the acceleration is defined as the ratio of change of the velocity.

This means that, if we have a change in the velocity, then we also have acceleration.

And by Newton's second law we know that:

F = m*a

Force equals mass times acceleration.

So if we have acceleration different than zero, then we should also have force different than zero.

So we must have a nonzero net force acting on it.

The correct option is D

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A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.90

kiruha [24]

Answer:

1 m/s² down

Explanation:

"Calculate the acceleration of the elevator, and find the direction of acceleration."

Sum of forces in the +y direction:

∑F = ma

N − mg = ma

0.9 mg − mg = ma

-0.1 mg = ma

a = -0.1 g

a = -1 m/s²

6 0

3 years ago

The water behind Grand Coulee Dam is 1000 m wide and 200 m deep. Find the hydrostatic force on the back of the dam. (Hint: the t

Vika [28.1K]

Answer:

The hydro static force on the back of the dam is $1.96\times10^{11}\ N$

Explanation:

Given that,

Width b= 1000 m

Depth d= 200 m

We need to calculate the average pressure

Using formula of average pressure

$P_{avg}=\rho\times g\times d_{avg}$

Put the value into the formula

$P_{avg}=1000\times9.8\times100$

$P_{avg}=980000\ Pa$

We need to calculate the hydro static force on the back of the dam

Using formula of force

$F = P_{avg}\times A$

Put the value into the formula

$F = 980000\times1000\times200$

$F=1.96\times10^{11}\ N$

Hence, The hydro static force on the back of the dam is $1.96\times10^{11}\ N$

7 0

3 years ago

Two electrons exert a force of repulsion of 1.2 N on each other. How far apart are they? The elementary charge is 1.602 × 10−19

sergejj [24]

The distance between the charges is 13.86 X 10⁴m

Explanation:

Given:

Force, F = 1.2N

Charge, q₁ = 1.602 X 10⁻¹⁹ C

k = 8.987 X 10⁹ Nm²/C²

Distance, d = ?

According to Coulomb's law:

$F = k\frac{q_1q_2}{r^2} \\\\$

Substituting the value in the formula we get:

$1.2 = 8.987X 10^9 X\frac{1.602 X 10^-^1^9 X 1.602 X 10^1^9}{r^2} \\\\1.2 = \frac{23.06 X 10^9}{r^2} \\\\r^2 = 19.22 X 10^9\\\\r = 13.86 X 10^4m$

Therefore, the distance between the charges is 13.86 X 10⁴m

5 0

3 years ago

In order to safely conduct any experiment in the laboratory, it is crucial that you

vekshin1

Lab Safety Rules:

Report all accidents, injuries, and breakage of glass or equipment to instructor immediately. Keep pathways clear by placing extra items (books, bags, etc.) on the shelves or under the work tables. If under the tables, make sure that these items can not be stepped on. Long hair (chin-length or longer) must be tied back to avoid catching fire. Wear sensible clothing including footwear. Loose clothing should be secured so they do not get caught in a flame or chemicals.Work quietly — know what you are doing by reading the assigned experiment before you start to work. Pay close attention to any cautions described in the laboratory exercises Do not taste or smell chemicals. Wear safety goggles to protect your eyes when heating substances, dissecting, etc. Do not attempt to change the position of glass tubing in a stopper. Never point a test tube being heated at another student or yourself. Never look into a test tube while you are heating it.Unauthorized experiments or procedures must not be attempted.Keep solids out of the sink. Leave your work station clean and in good order before leaving the laboratory. Do not lean, hang over or sit on the laboratory tables. Do not leave your assigned laboratory station without permission of the teacher. Learn the location of the fire extinguisher, eye wash station, first aid kit and safety shower. Fooling around or "horse play" in the laboratory is absolutely forbidden. Students found in violation of this safety rule will be barred from participating in future labs and could result in suspension. Anyone wearing acrylic nails will not be allowed to work with matches, lighted splints, Bunsen burners, etc. Do not lift any solutions, glassware or other types of apparatus above eye level. Follow all instructions given by your teacher.Learn how to transport all materials and equipment safely. No eating or drinking in the lab at any time!

3 0

3 years ago

The tape in a videotape cassette has a total

Softa [21]

Answer:

1.37 rad/s

Explanation:

Given:

Total length of the tape is, $d= 297$ m