Aradiator has an emissivity of 0.7 and its exposed area is 1.2 m2. the temperature of the radiator is 850c and the surrounding temperature is 200c. what is the net heat flow rate from the radiator? ( = 5.67x10-8 w/m2k4)

An ideal spring has a spring constant (force constant) of 2500 n/m, is stretched 4.0 cm, how much elastic potential energy does it possess? (a) 3j (b) 0.00j (c) 1j (d) 2j (e) 4j

You will be galileo perform the experiment to determine if objects with different mass fall at the same, or different, rates in the air and in a vacuum. (refer to the walk-through video to locate the online lab within the online textbook).

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".