1. The acceleration equation of a certain particle is a=2t, after 4s, its velocity reaches 20m/s, then the initial velocity of the particle movement is ) ms B Sms 2.

Change in velocity is the integral of all the differential accelerations acting over the period of acceleration.

20 = u + t²

20 = u + 4² - 0²

20 = u + 16

u = 4 m/s

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods