Question

You are testing a new t-shirt cannon. You decide to fire the t-shirts vertically straight up in the air so that you do not have to walk to pick up the launched t-shirts. First, a green t-shirt is launched vertically upwards with a speed of 12 m/s. Exactly 1.0 s later, a blue t-shirt is launched vertically upwards with a speed of 18 m/s. At what time (after the launch of the first green t-shirt) will the two shirts collide, and at what height above the cannon? You may ignore air resistance throughout the problem.

Answer 1

Initial vertical velocity of green t-shirt which was launched first,

Let be the time taken by the t-shirts to collide

Initial vertical velocity of blue t-shirt which was launched 1s after the green t-shirt,

Let be the time taken by blue t-shirt to collide with green t-shirt

Given ----------(1)

Let be the height above the cannon where the t-shirts collide

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Use formula

Consider the green t-shirt

----------(2)

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Consider the blue t-shirt

Put (1) in the above equation

Put (2) in the above equation

ANSWER:

Note: The t-shirts will collide 1.45s after the green t-shirt was launched and 0.45s after the blue t-shirt was launched.

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Put value of in (2)

ANSWER:

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