A ball of mass m = 2.0 kg is connected to 2 ropes. The two ropes are connected to a pole that is rotating at a constant angular speed ω. The two ropes have an equal tension T. The rope on the bottom makes an angle of 60◦ with the pole and and the rope on the top makes an angle of 60◦ with the horizontal. The ball is going around in a circle at a constant speed v and a radius r = 0.87 m (uniform circular motion).
Problem 1: What is v, the speed of the ball?
Problem 2: What is T, the tension on each of the ropes?

What are similarities and differences of reflection, refraction, diffraction and absorption?

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".

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is as it changes into other forms of energy.