Math CentralQuandaries & Queries


David, a student:

A juggler tosses a ball into the air with a velocity of 40ft/sec from a height of 4 ft. Use s= -6t2 + vot+so to find how long it takes for the ball to return to the height of 4 ft.

I was wondering how should i start this out, and can you give me a brief explanation on the formula they ask you to use? thx

Hi David,

You are actually given the formula to find time: s= -6t2 + vot+so

s - distance at time t. In this case we want to find t when s = 4 ft

vo - initial velocity is given to be 40 ft/s

so - initial distance is given to be 4 ft

Now it is just a matter of plugging the given information into the formula:

4= -6t2 + 40t+4

Now you can collect like terms and solve by factoring or using the quadratic equation.

Hope this helps,







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