Question

An object is dropped off a tower. Its height h (in feet) above the ground after t seconds is given by h(t)=576-16t^2. Which of the following is the velocity when it strikes the ground? I know the answer is -192 ft/sec. I just dont know why

Answer 1

If you have learnt differentiation, you'd observe that if you take differential of the equation, you'd get the velocity of the object, and now, when you replace h(t) with 0, you'd get the point of time when the height is zero, now use the given data, to find out the velocity when it strikes the ground. More specifically, the time at which h = 0 is 6s, now plug that into the diff. and you'll get -32*t, where t = 6, therefore -32*6, which is -192