Level 1: At the Top of a Throw the Ball Stops. Is Its Acceleration Zero?
Throw it at an angle, and find the curve at the top.
A ball is thrown at 30 m/s at 60° above the horizontal (g = 10 m/s²). At the highest point of its path, the radius of curvature of the path is:
At the highest point the velocity is horizontal, u cos 60° = 15 m/s, and the acceleration g is vertical, so all of g acts at right angles to the velocity, as a centripetal acceleration.
The path curves with a radius of 22.5 m at the top. Using the launch speed instead, 30²/10 = 90 m, is the usual mistake; only the speed at the top, and the part of g at right angles to it, count.
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