Question

josh is standing on the top of a building that is 425 feet tall. He throws a penny up into the air with an initial of 32 ft/sec. How long does it take for the penny to hit the ground?
Y = -4.9x^2 + 32x + 425

A. 10 seconds

B. 6.25

C. 400

D. 0 seconds

Answer 1

Answer:

A

Step-by-step explanation:

cause it will be more faster just because it is in a solid phase or it is solid

Answer 2

The time taken to hit the ground is 6.25 sec.(Option B)

How to calculate time?

It is given that penny follows the trajectory:

$y = -4.9x^2 + 32x + 425$

Differentiating it we get:

$\dfrac{dy}{dx} =-9.8x+32$

At y=425, it is obvious that x=0

So dy/dx at x=0 is 32.

Now the vertical component of the velocity is 32sinФ (where Ф is the angle at which penny is thrown).

Ф$=\tan^{-1}(32)$

Vertical component=$32*\sin(\tan^{-1}(32))$=31.98 ft/sec

Now applying the equation of motion: acceleration=-32ft/sec^(2)

u=31.98ft/sec   s=-425   t=?

$s=ut+\frac{1}{2} at^{2}$

$-425=31.98t-16t^2$

$16t^2-31.98t-425=0$

Solving the quadratic equation we get:

t=6.249 sec≅6.25 sec

Therefore, the time taken is 6.25 sec.

To know more about equation of motion refer:https://brainly.com/question/24966506

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