Aball is dropped from the top of the empire state building to theground below. the height, y, of the ball above the ground (in feet)is given as a function of time, t (in seconds) by

.

(a) find the velocity of the ball at time t. what is the sign ofthe velocity? why is this to be expected?

(b) show that the acceleration of the ball is a constant. what arethe value and sign of this constant?

(c) when does the ball hit the ground, and how fast is it going atthat time? give your answer in feet per second and in miles perhour (1ft/sec=15/22mph).

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.