A projectile starting from ground hits a target on the ground located at a distance of 100 meters after 4 seconds. a) What is the size of the angle θ?
b) At what initial velocity was the projectile launched?

Answer(b) 60 miles per hour;

The geological theory that states that pieces of earth's lithosphere are in constant slow motion is the theory of plate tectonics.

Planck decided to assume that atoms could only vibrate at certain frequencies that were whole numbers eg 2f, 3f and so on. others used to think that atoms vibrate continuously

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.