index

Prj51 The potato gun

A small mass is projected from the top of a 20-m tall building with a "potato gun" at an initial speed of 40 m/s and angle 35° to the horizontal.

What is the range from the bottom of the building?

What is the maximum height?

What are the velocity components as the mass strikes the ground?

Diagram the problem and place the origin of an x-y coordinate system at the base of the building.

Now write the six equations:

To find the range first find the time of flight. Use the y = . . . equation with y = 0.

The quadratic is

The range, the value of x when t = 5.4 is

The maximum height occurs when v_y = 0.

and when t = 2.3 s, the height is

Note: This is not a symmetrical parabola so don't use 1/2 the time of flight for the maximum height calculation.

Click on "The Ultimate Potato Gun" link for a picture of a Gatling-type potato gun. If you are interested in potato guns there are several sites listed on the search engines.