Ball A is projected vertically upward at 30 m/s from a point P. Four seconds later, ball B is also launched vertically upwards from the same point P and also at 30 m/s. For how long has ball A been in motion when two balls collide

The time of motion of ball A before they collide is 5.1 seconds.

The two balls will collide at a time "t" when they attain a certain height "h".

The equation of motion of the two balls is given as follows;

when they collide;

Thus, the time of motion of ball A before they collide is (1.1 + 4) = 5.1 seconds.

Learn more about time of motion here:

half of a circle

explanation:

the arrow and the top of the circle is matching together. it is not a polygon because a polygon would always be the same shape. therefore, an half of a circle is called semicircle so you would find the radius of it.