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3 years ago

A football player runs down a field with a speed of 8 m/s. How long will it take him to run 20m?

2 answers:

5 0

To find the answer for this question, you simply need to divide 20 by 8, which is the speed he is traveling.

20 / 8 = 2.5

The football player will run 20 yards in 2 1/2 seconds.
Hope that helped! =)

Charra [1.4K]3 years ago

3 0

Answer:

Time taken, t = 2.5 seconds

Explanation:

It is given that,

Speed of the football player, v = 8 m/s

We have to find time taken by the football player to run 20 m. It can be calculated suing the formula of speed of the player i.e.

$s=\dfrac{d}{t}$

d = distance

t = time taken

$t=\dfrac{d}{s}$

$t=\dfrac{20\ m}{8\ m/s}$

t = 2.5 seconds

Hence, time taken by the football player is 2.5 seconds

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A body of mass 120 g is taken vertically upwards to reach the height of 5m,claculate work done

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3 years ago

A jet plane comes in for a downward dive as shown in the figure below.

xxTIMURxx [149]

The solution would be like this for this specific problem:

5.5 g = g + v^2/r 
4.5 g = v^2/r 
v^2 = 4.5 g * r 
v = sqrt ( 4.5 *9.81m/s^2 * 350 m) 
v = 124 m/s

So the pilot will black out for this dive at 124 m/s. I am hoping that these answers have satisfied your query and it will be able to help you in your endeavors, and if you would like, feel free to ask another question.

8 0

3 years ago

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Given three vectors A = 24i + 33j, B = 55i - 12j and C = 2i + 43j (a) Find the magnitude of each vector. (b) Write an expression

slega [8]

Answer:

(a) , . and .

(b) $\vec A - \vec C=22 \hat i -10 \hat j$ .

Explanation:

Given that,

and

$\vec {C}=2 \hat i +43 \hat j$

(a) The magnitude of a vector is the square root of the sum of the square of all the components of the vector, i.e. for a ,.

So, the magnitude of the is

$|\vec A|=\sqrt {24^2+ 33^2}$

$\Rightarrow |\vec A|=\sqrt {1665}$

The magnitude of the is

$|\vec B|=\sqrt {55^2+ (-12)^2}$

$\Rightarrow |\vec B|=\sqrt {3169}$

And, the magnitude of the is

$|\vec C|=\sqrt {2^2+ 43^2}$

$\Rightarrow |\vec C|=\sqrt {1853}$

(b) The difference between the two vectors is the difference between the corresponding components of the vectors. So, the required expression of is

$\vec A - \vec C=(24 \hat i +33 \hat j) - (2 \hat i +43 \hat j)$

$\Rightarrow \vec A - \vec C=24 \hat i +33 \hat j - 2 \hat i -43 \hat j$

$\Rightarrow \vec A - \vec C=22 \hat i -10 \hat j$

$\vec A - \vec N=(24 \hat i +33 \hat j) - (55 \hat i -12 \hat j)$

$\Rightarrow \vec A - \vec B=24 \hat i +33 \hat j - 55\hat i +12 \hat j$

$\Rightarrow \vec A - \vec B=-31 \hat i +45 \hat j\;\cdots (i)$

The magnitude of is

$|\vec A - \vec B|=\sqrt {(-31)^2+55^2}$

$\Rightarrow |\vec A - \vec B|=\sqrt {3986}$

$\Rightarrow |\vec A - \vec B|=63.13$

Now, if a vector $\vec V= -\alpha \hat i +\beta \hat j$ in 3rd quadrant having direction $\theta$ with respect to $\hat i$ direction, than

in the anti-clockwise direction.

Here, from equation (i), for the vector $\vec A - \vec C$ , $\alpha=31$ and $\beta=45$ .

$\Rightarrow \theta = \pi-\tan ^{-1}\left(\frac {45}{31}\right)$

180°-55.44° [as \pi radian= 180°]

124.56° in the anti-clockwise direction.

(d) Vector diagrams for $\vec A +\vec B$ and $\vec A - \vec B$ has been shown

in the figure(b) and figure(c) recpectively.

Vector $\vec A - \vec B$ is in 3rd quadrant as calculated in part (c).

While Vector $\vec A +\vec B=(24 \hat i +33 \hat j)+(55 \hat i -12 \hat j)$

$\Rightarrow \vec A +\vec B=79 \hat i +21 \hat j$ , which is in 1st quadrant as both the components are position has been shown in figure(b).

6 0

3 years ago

you see an insect egg lying on a leaf. What is the next step? Name or describe the stage you would expect to see come out from t

Marianna [84]

Answer:

Metamorphosis are the series of processes involved in the development of organisms, mostly insects after the egg is hatched.

Insects undergo complete or incomplete metamorphosis

Complete metamorphosis involves 4 stages which is the development from egg to larva to pups to adults in a step wise manner e.g butterfly, moth etc

Egg—> Larva—> Pupa—> Adults

In incomplete metamorphosis the stages are 3 and it involves development from egg to nymph to adults. E.g cockroach

Egg—> Nymph—> Adults

4 0

3 years ago

What would happen if water could not condense in the atmosphere

Harrizon [31]

-- As more water evaporated from lakes, rivers, ponds, and people, the
water vapor in the atmosphere would build up and build up and build up,
until the atmosphere could not hold any more water vapor.

-- The water would stay there in the atmosphere. There would never be
any more rain, sleet, hail, fog, drizzle, mist, or snow.

-- Rivers flow out of lakes and ponds, carrying lake water to the sea.
Rain keeps the lakes refilled.
The lakes would eventually dry out as the rivers drained them, and then
the rivers would run dry. It would be the end of trees, forests, and farming.

-- At the instant when the atmosphere became full of all the water vapor
it could hold, all evaporation on Earth would stop.

. . . . . When you washed the dishes, you could leave them standing in the
drainer rack for a week, but they would never dry.

. . . . . You could hang up your bath towel and the laundry in your room or
in the back yard, but it would never dry.

. . . . . When you boiled a pot of water on the stove, I'm not sure exactly
what would happen, but I know that the steam could not just rise from
the pot and disappear. The atmosphere couldn't absorb it, so I guess
it would be this dense cloud of boiling hot fog that would rise from the pot
and fill the kitchen. If you walked through it, it would swirl and drift around.
Eventually it would settle on the walls, and when the droplets got big enough,
they would run down the walls and make puddles on the floor.

. . . . . It would be pretty bad for people and animals. We generate a lot of heat
inside our bodies, and we get rid of the heat by perspiring. Moisture comes
out of our skin and evaporates into the air, which takes heat with it.
If the atmosphere was full with as much water vapor as it could hold, then
perspiration could not evaporate. We would ALWAYS be walking around
in 100% humidity, with water running off of our skin onto the floor. The only
way we could cool ourselves would be to pour cold water on ourselves.
Anybody who didn't do that every couple of minutes would pass out from
heat exhaustion, as his inside temperature got too high.

Our dogs don't even perspire. The only way they can get rid of heat is to
make their tongues wet and then blow air over it. That's why when they
run, or when the weather is hot, they drink a lot and pant fast. The water
evaporating from their tongues is the only way they can get rid of heat.
If the atmosphere could not take any evaporation, then our dogs would
probably stop moving around at all, and just lay around all day, drinking
cold water.

In short, I think it's accurate to say that if condensation of water in the
atmosphere stopped, then evaporation would stop, and it would only be
a matter of time before life on Earth stopped.

7 0

2 years ago

Read 2 more answers