What do you think a black hole is

Who first calculated the orbits of comets based on historical records dating back to antiquity?

What is the relationship between kelvin and Celsius

The sketch shows a painter's scaffold in mechanical equilibrium. The person in the middle weighs 225 N, and the tension in each rope is 300 N. What is the weight of the scaffold?

While entering a freeway, a car accelerates from rest at a rate of 2.1 m/s^2 for 14.5 s. How far does the car travel in those 14.5 s, in meters? What is the car's final velocity, in meters per second?

Which sentence states Newton's third law? If two objects collide, each object exerts a force in the same direction as the other. If two objects collide, each object exerts a force equal to and in the opposite direction of the other.

Frictional force is ___of area of contact

Can you calculate gravitational potential energy by using what type of equation?

An astronomer is measuring the electromagnetic radiation emitted by two stars, both of which are assumed to be perfect blackbody emitters. For each star she makes a plot of the radiation intensity per unit wavelength as a function of wavelength.

Which of the following is true? A depression is a recession that is mild and relatively brief. The expansions and contractions of real world business cycles last varying lengths of time and often differ in magnitude.

A pure lead bar 10 cm long is maintained with one end at T=300 K and the other at 310 K. The thermoelectric potential difference thus induced across the ends is 12.8? V. Find the thermoelectric power for lead in this temperature range