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3 years ago

8

A topic list is a list of important content and material which will be covered on a test. Please select the best answer from t

he choices provided T or F

2 answers:

Sindrei [870]3 years ago

8 0

Answer:

True on e2020

Explanation:

just took the test!

Iteru [2.4K]3 years ago

6 0

Sounds T to me. My teacher used to give those out.

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If your speed slows down you will have what acceleration?

vitfil [10]

When speed slows down you have kinetic energy.

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4 years ago

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As you approach a bicyclist traveling in your lane, adjust your speed and position and do not pass if the road is too _______ fo

tatiyna

Answer:

correct answer is narrow

Explanation:

solution

when we pass someone riding bicycle ahead you then we should decrease our speed and increase the distance between you and bicyclist

and we should ride on road with very predictable manner and we should ride in straight line and if If road is too narrow for a bicycle

then we should ride vehicle to travel side by side so bicyclist should occupy lane until it safe

so here correct option is narrow

5 0

3 years ago

If an atom has a mass number of 23, which of the following is always true?

WINSTONCH [101]

The number of protons in the nucleus does not equal the number of nuetrons

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3 years ago

Lottery balls are thrown into a hopper and are set into motion by air forced through the container. each ball has a mass of 0.00

Marina CMI [18]

In this three body system total kinetic energy remains constant:
$E_{k} = constant =0.0268 J$

$E_{k} = E_{k1}+ E_{k2}+ E_{k3}$
If we assume that upwards movement is positive and downwards movement is negative the formula is:
$E_{k} = E_{k1}- E_{k2}+ E_{k3}$

Formula for kinetic energy is:
$E_{k} = \frac{m v^{2} }{2}$

Now we have:
$E_{k} = \frac{m v_{1} ^{2} }{2} -\frac{m v_{2} ^{2} }{2} +\frac{m v_{3} ^{2} }{2} \\ E_{k} = \frac{m}{2} (v_{1} ^{2}-v_{2} ^{2}+v_{3} ^{2}) \\ \\ 0.0268= \frac{0.0044}{2} (1.3 ^{2}-1.66^{2}+v_{3} ^{2}) \\ \\ 0.0536=0.0022(1.69-2.7556+v_{3} ^{2}) \\ \\ v_{3} ^{2}=25.43 \\ \\ v_{3} =+-5.04$

We got two solutions: positive and negative. The speed is 5.04 m/s and direction can be upwards and downwards.

3 0

3 years ago

A 55.6-kg skateboarder starts out with a speed of 2.44 m/s. He does 80.4 J of work on himself by pushing with his feet against t

Vikentia [17]

(a) -1620.8 J

The initial kinetic energy of the skateboarder is:

$K_i = \frac{1}{2}mu^2 = \frac{1}{2}(55.6 kg)(2.44 m/s)^2=165.5 J$

where m is the skateboarder's mass and u his initial speed;

While the final kinetic energy is

$K_f = \frac{1}{2}mv^2 = \frac{1}{2}(55.6 kg)(7.24 m/s)^2=1457.2 J$

where v is his final speed.

So the change in kinetic energy is

$\Delta K=K_f - K_i = 1457.2 J -165.6 J = 1291.6 J$

According to the work-energy theorem, the change in mechanical energy (kinetic+potential) of the skateboarder is equal to the work done on it:

$\Delta K + \Delta E_p = W + W_f$

where

$W = 80.4 J$ is the work done by the skateboarder on himself

$W_f = -244 J$ is the work done by friction

$\Delta E_p = E_p_f - E_p_i$ is the change in gravitational potential energy

Solving for $\Delta E_p$ ,

$\Delta E_p = W+W_f - \Delta K=80.4 J - 244 J - 1457.2 J = -1620.8 J$

(b) 2.97 m

The change in potential energy of the skateboarder can be written as

$\Delta E_p = mg \Delta h$

where

m = 55.6 kg is the mass

g = 9.8 m/s^2 is the acceleration of gravity

$\Delta h$ is the change in vertical height of the skateboarder

Solving for $\Delta h$ ,

$\Delta h = \frac{\Delta E_p}{mg}=\frac{-1620.8 J}{(55.6 kg)(9.8 m/s^2)}=-2.97 m$

Where the negative sign means the skateboarder has moved downwards. Since we are interested only in the absolute value, the answer is

h = 2.97 m

7 0

3 years ago