4. Collecting the sun's energy with solar panels, heating water with that energy, and storing the heated water to use the energy later. dont know what this is its for a cross word in physical science and it starts with an a

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".

You walk 45 m to the north, then turn 90° to your right and walk another 45 m how far are you from where you originally started? a.45 m b.41 m c.85 m d.64 m

An unknown mineral sample has a mass of 318 g and a volume of 120 cm³. which mineral could the sample be? a. gypsum (density = 2.3 g/cm³) b. quartz (density = 2.65 g/cm³) c. apatite (density = 3.1 g/cm³) d. zircon (density = 4.65 g/cm³)