Aball is thrown directly upward from a height of 3 ft with an initial velocity of 28 ft/sec. the function s(t)equalsminus16tsquaredplus28tplu s3 gives the height of the ball, in feet, t seconds after it has been thrown. determine the time at which the ball reaches its maximum height and find the maximum height.

Explanation:

Position of the ball as a function of time is given as

now we know that when ball will attain maximum height then the differentiation of the position with respect to time will become zero

so we have

now the maximum height is given as

the answer is a)

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electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia