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3 years ago

12

A man wishes to row the shortest possible distance from north to south across a river which is flowing at 2 km/hr from the east.

He can row at 4 km/hr. (a) In which direction should he steer

1 answer:

sweet-ann [11.9K]3 years ago

8 0

From the diagram we have that

$sin\theta = \frac{2}{4}$

$\theta = sin^{-1} (\frac{1}{2})$

$\theta = 30\°$

Therefore the direction is 30° from east of south

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If a car is traveling 60 mph, its tires may have an rpm of 840. How many revolutions do the car’s tires make in one second?

Varvara68 [4.7K]

Forget about the car's speed. You don't need it.

The tires spin 840 rpm. That's 840 <em>Revolutions per Minute</em> .

There are 60 seconds in 1 minute. So something that happens 840 times in 1 minute happens (840 / 60) times every second.

(840 rev per minute) / (60) = <em>14 revs per second</em> .

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3 years ago

The number of mushrooms needed by a pizza restaurant is given by the

kupik [55]

Answer: 24

Explanation:

Given the following equation:

$g=3n$

Where $g$ is the number of mushrooms in a pizza and $n$ the number of pizzas.

If we know the restaurant will make 8 pizzas ( $n=8$ ), then:

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3 years ago

You run a race with your friend. At first you each have the same kinetic energy, but then you find that she is beating you. When

Blizzard [7]

Answer:

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Explanation:

Let m1 and v1 denote your mass and velocity respectively

Let m2 and v2 denote your friends mass and velocity respectively

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Since your kinetic energies are the same hence

$0.5m1(v1)^{2}=0.5m2(v2)^{2}$

$m1(v1)^{2}=m2(v2)^{2}$ and making m2 the subject then

$m2=\frac { m1(v1)^{2}}{(v2)^{2}}$

Since v2 is v1+0.28v1=1.28v1

Substituting m1 for 86 Kg

$m2=\frac { 86 Kg(v1)^{2}}{(1.28v1)^{2}}= 52.49023\approx 52.49 Kg$

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The speed of the plane

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3 years ago