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2 years ago

12

Chris walks 25 m in the positive direction on a number line, then turns around and walks 15 m in the opposite direction. What is

the magnitude of the displacement of Chris?
A. -10 m
B. 40 m
C. 10 m

1 answer:

7nadin3 [17]2 years ago

3 0

Answer:

$|d| = |(25 - 15)| \\ |d| = 10 \: m$

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The image shows the positions of a car on a roller coaster track. Arrange the cars in order based on their gravitational potenti

RideAnS [48]

Correct order, from lowest potential energy to highest potential energy:

E - C - D - B - A

Explanation:

The gravitational potential energy of the car is given by:

$U=mgh$

where

m is the car's mass

g is the gravitational acceleration

h is the height of the car relative to the ground

In the formula, we see that m and g are constant, so the potential energy of the car depends only on its height above the ground, h. The higher the car from the ground, the larger its potential energy. Therefore, the position with least potential energy will be E, since the height is the minimum. Then, C will have more potential energy, because the car is at higher position, and so on: the position with greatest potential energy is A, because the height of the car is maximum.

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3 years ago

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List 3 cases in which potential energy becomes kinetic energy and three cases in which kinetic energy becomes potential energy.

Mrrafil [7]

Answer:

when you open a can of pop

when you jump on your bed

Explanation:

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3 years ago

How could you group pennies,nickels, and dimes together

julsineya [31]

There isn't a direct answer to this, but I can show you!

This is how you group Pennies, Nickels, and Dimes.

1 Penny= 1 cent.

1 Nickel= 5 cents.

1 Dime= 10 cents.

Imagine if there was 5 pennies, 3 dimes, and 8 Nickels.

That might seem like a lot of numbers, but it's pretty simple!

You know how pennies are worth 1 cent? If we had 5 pennies, that would be 5 cents.

1+1+1+1+1=5 cents.

Then, we have 3 dimes. Dimes are each 10 cents.

So, 10x3 (If you know multiplication, if not, you will learn it later) :)

10+10+10= 30 cents.

Now, nickels. We have 8 nickels! Remember, each nickel is 5 cents.

5+5+5+5+5+5+5+5=

40 Nickels.

Now add all of the coins up.

5 cents + 30 cents + 40 cents = 75 cents!

I hope this helped! If you need more help, you can ask me. :)

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2 years ago

Firemen are shooting a stream of water at a burning building. A high-pressure hose shoots out the water with a speed of 26.0 m/s

alekssr [168]

Answer:

a) θ = 58.3º

b) vfh = 13.7 m/s

c) g = -9.8 m/s2

d) h = 22.2 m

e) vfb = 15.5 m/s

Explanation:

a)

Assuming that gravity is the only influence that causes an acceleration to the water, due to it is always downward, since both directions are independent each other, in the horizontal direction, the water moves at a constant speed.
Since the velocity vector has a magnitude of 26.0 m/s, we can find its horizontal component as follows:
vₓ₀ = v * cos θ (1)
where θ is the angle between the water and the horizontal axis (which we define as the x-axis, being positive to the right).
Applying the definition of average velocity, taking the end of the hose like the origin, and making t₀ = 0, we can write the following expression:

$x_{f} = v_{ox} * t = v_{o} * cos \theta * t (2)$

Replacing by the givens of xf = 41.0m, t = 3.00 s, and v=26.0 m/s, we can solve for the angle of elevation θ, as follows:

$cos \theta = \frac{x_{f} }{v*t} = \frac{41.0m}{26.0m/s*3.00s} = 0.526 (3)$

⇒θ = cos⁻¹ (0.526) = 58.3º (4)

b)

At the highest point in its trajectory, just before starting to fall, the vertical component of the velocity is just zero.
Since the horizontal component keeps constant during all the journey, we can conclude that the speed at this point is just v₀ₓ, that we can find easily from (1) replacing by the values of v and cos θ, as follows:
vₓ₀ = v * cos θ = 26.0 m/s * 0.526 = 13.7 m/s. (5)

c)

At any point in the trajectory, the only acceleration present is due to the action of gravity, which accepted value is -9.8 m/s2 (taking the upward direction on the vertical y-axis as positive)

d)

Since we know the time when the water strikes the building, it will be the same for the vertical movement, so, we can use the kinematic equation for vertical displacement, as follows:

$\Delta y = v_{oy} * t - \frac{1}{2} *g*t^{2} (6)$

Our only unknown remains v₀y, which can be obtained in the same way than the horizontal component:
v₀y = v * sin θ = 26.0 m/s * 0.85 = 22.1 m/s (7)
Replacing (7) in (6), we get:

$\Delta y = 22.1 m/s* 3.0s - \frac{1}{2} *9.8m/s2*(3.00s)^{2} = 22.2 m (8)$

e)

When the water hits the building the velocity vector, has two components, the horizontal vₓ and the vertical vy.
The horizontal component, since it keeps constant, is just v₀x:
v₀ₓ = 13.7 m/s
The vertical component can be found applying the definition of acceleration (g in this case), solving for the final velocity, as follows:

$v_{fy} = v_{oy} - g*t (9)$

Replacing by the time t (a given), g, and v₀y from (7), we can solve (9) as follows:

$v_{fy} = 22.1 m/s - 9.8m/s2*3.00s = -7.3 m/s (10)$

Since we know the values of both components (perpendicular each other), we can find the magnitude of the velocity vector (the speed, i.e. how fast is it moving), applying the Pythagorean Theorem to v₀ₓ and v₀y, as follows:

$v_{f} = \sqrt{(13.7m/s)^{2} +(-7.3m/s)^{2}} = 15.5 m/s (11)$

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3 years ago

021. The hydrostatic pressure 'P' of a liquid column depends upon the

Lana71 [14]

Answer:

A

Explanation:

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where 'h' is the ht of the liq column and ρ is the density of the liquid and 'g' is the effective acceleration, but as far as hydroSTATICS is concerned, g stands for the acceleration due to gravity

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2 years ago