Geometry Problems, Math Problems

Problem of the Day: 1/19/13

A stop sign is cut out of this 2-foot square piece of metal, as shown in the figure below. The side lengths that coincide with the edges of the metal are 1 foot, as not shown in the figure below. How much metal is not used?

20130118-213240.jpg

Solution to yesterday’s problem:

We are given the initial height i, so our equation becomes h=-16t^2+3600. To find the time when h=0, let’s substitute in the variable and solve:

0=-16t^2+3600

Moving the variable to the other side to handily avoid a negative coefficient, we get

16t^2=3600

Taking the square root of both sides,

4t=60

Algebraically speaking, it could of course be positive or negative 60; but we can ignore the negative value because there would be no negative time. Finally, we arrive at the solution that the object would hit the ground 15 seconds after dropping.

(Diagrams created with the Isosceles iOS app.)

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s