A student throws a rock upwards. The rock reaches a maximum height 2.4 seconds after it was released. How fast was the rock thrown?

Suppose you use a machine that gives you a mechanical advantage of 2 to achieve an output force of 30newtons what must the input force be

Density of salty water as compared to the density of pure water is(a) is less(b) is always equal(c) is always more(d) may be less or more

The long handle on a rake is a(n) a. lever b. screw c. wedge d. inclined plane