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deff fn [24]
3 years ago
6

We drive at a speed of 20 km/h for 3 hours. Then we drive 4 hours at 30 km/h. Calculate our average speed.

Physics
2 answers:
SashulF [63]3 years ago
6 0

Answer

A. T. Q

Total distance travelled by total time taken

<em><u>speed = Total distance / Total timeAverag</u></em><em><u>e</u></em>

Here Total distance travelled is 20 + 40 = 60 km by the car

total time taken is 1 + 3 = 4 hours

here the average speed of the car is given by

S=60/4=15km/hr

this is answer by the question

Afina-wow [57]3 years ago
4 0

First speed = 20km/h

Time = 3 hours

Distance = 3×20

<h3> = <u>60 km</u></h3>

Second speed = 30km/h

Time = 4 hours

Distance = 4×30

<h3> = <u>120 km</u></h3>

Total distance = 60+120 = <u>180km</u>

Total time = 3+4 =<u> 7 hours</u>

Average speed = 180/7

<h3> = <u>25.71</u><u> </u><u>km</u><u>/</u><u>h</u></h3>

Hope this will help...

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astra-53 [7]

Answer:

a)

Y0 = 0 m

Vy0 = 15 m/s

ay = -9.81 m/s^2

b) 7.71 m

c) 3.06 s

Explanation:

The knowns are that the initial vertical speed (at t = 0 s) is 15 m/s upwards. Also at that time the dolphin is coming out of the water, so its initial position is 0 m. And since we can safely assume this happens in Earth, the acceleration is the acceleration of gravity, which is 9.81 m/s^2 pointing downwards

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ay = -9.81 m/s^2 (negative because it points down)

Since acceleration is constant we can use the equation for uniformly accelerated movement:

Y(t) = Y0 + Vy0 * t + 1/2 * a * t^2

To find the highest point we do the first time derivative (this is the speed:

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We equate this to zero

0 = Vy0 + a * t

0 = 15 - 9.81 * t

15 = 9.81 * t

t = 0.654 s

At this time it will have a height of:

Y(0.654) = 0 + 15 * 0.654 - 1/2 * 9.81 * 0.654^2 = 7.71 m

The doplhin jumps and falls back into the water, when it falls again it position will be 0 again. So we can equate the position to zero to find how long it was in the air knowing that it started the jump at t = 0s.

0 = Y0 + Vy0 * t + 1/2 * a * t^2

0 = 0 + 15 * t - 1/2 * 9.81 t^2

0 = 15 * t - 4.9 * t^2

0 = t * (15 - 4.9 * t)

t1 = 0 This is the moment it jumped into the air

0 = 15 - 4.9 * t2

15 = 4.9 * t2

t2 = 3.06 s This is the moment when it falls again.

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5 0
3 years ago
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Bogdan [553]

Complete question:

Suppose the wavelength of the light is 550 nm . How much farther is it from the dot on the screen in the center of fringe E to the left slit than it is from the dot to the right slit? Fringe C is the central maximum.

Check the image uploaded.

Answer:

The difference is 1100 nm

Explanation:

A bright fringe creates constructive interference, the wavelength is always in a multiple form.

At center fringe, the difference is (550 nm)(0) = 0

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Thus, for nth maxima, the difference is (550 nm)(n)

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Answer:

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