A mass = [m] kg is tied to a rope that is wrapped around a…

A mass = [m] kg is tied to a rope that is wrapped around a pulley and connected to a spring with spring constant . The rope and pulley are essentially massless and frictionless. At the initial position of the system (illustrated by top block), the spring is at equilibrium length. When the block has dropped a distance = [d] m, the system is again at rest. What is the value of the spring constant ? Please give your answer in units of N/m.

At its most distant, Pluto is 7.5 billion km from Earth. We…

At its most distant, Pluto is 7.5 billion km from Earth. We would like to leave Earth and stop at Pluto by accelerating at for half of this distance and decelerating at for the other half. How long does it take to make this trip? (Note you can’t actually carry enough fuel to accelerate continuously over the length of this trip. It’s just a thought exercise.)

You are tasked with surveying your town to find the best pla…

You are tasked with surveying your town to find the best playground in the city.  You start by dividing the town into 6 regions.  You need  120 people to survey.  You plan to randomly sample 20 people from each region.     Which type of sampling method is being used?