Einstein's theory of gravity allows for many of the more interesting phenomena in our universe, such as black holes. Qualitatively, we can think of a black hole as a place where gravity strong enough to curve space-time to the point of actually punching a hole in it. If the Sun makes a gentle dip in space-time, a black bole creates a bottomless pit. It's difficult to imagine what any structure in four dimensions looks like since most of us can only see (and think) in three, but it is possible to calculate mathematically what the results of space-time curvature should be.

Unfortunately, the mathematics are too complicated for this course. Fortunately (or perhaps Unfortunately!), it is highly unlikely that any of us will ever find ourselves in a place where Newton's laws arc not a completely suitable way to describe the gravitational interaction. In September 20IS scientists announced the detection of Gravitation& Waves at the LIGO observatory. This discovery provides further evidence for tinsteirt's General Theoz-y of Relativity showing the existence of the predicted waves traveling at the speed of light from the merger of two black holes. What an amazing discovery!

Homework

I. If you have a mass of 60 kg, what is your weight in Newtons? Find it using the ace/titration of gravity on Earth and with Newton's equation for gravitational force.

2. Astronauts can carry much more mass on the moon. One astronaut can lift 2000 N on the moon (g= 1.7 m/s/s) How much would this weigh on Earth?

3. a. What is your mass in kg? To find it divide your weight in pounds by 2.2 lbs./kg. (You may lie about Wit weight as long as you use one that is actually possible for a human.)

b. All medication is dispensed in the metric system. Ibuprofen is to be taken at the amount of 10mg of medicine for each kg of patient mass (maximum prescribed dose). What is the maximum amount of ibuprofen you could take without overdosing?