A spaceship captain lands on an unknown planet. Before venturing forth, he needs to find out the free fall acceleration on that planet
All he has available to him is some thin light string, a stopwatch, and a small 2.75-kg metal ball (it was a rough landing). So he lets the ball swing from a 1.5-m length of the string, starting at rest, and measures that it takes 1.9 s for it to swing from the place where he released it to the place where it first stops as it reverses direction. What is the free fall acceleration on this planet?
4.1 m/s2
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Two pistons push down on the fluid filling two cylinders connected by a narrow hose, as shown in the figure. The area A1 is 1 square inch, and the area A2 is 10 square inches. A force of 4 pounds is exerted downward on piston 1, as shown
 The pressure on A2 is 40 psi. a. True b. FalseSuppose we observe a source of X-rays that varies substantially in brightness over a period of a few days. What can we conclude?
A) The X-ray source is a quasar. B) The X-ray source contains a black hole with an accretion disk. C) The X-ray source is no more than a few light-days in diameter. D) The X-ray source must have a strong, rapidly varying magnetic field. E) We are seeing the rapid orbit of two stars in a binary system.
At a certain instant, coil A is in a 10-T external magnetic field and coil B is in a 1-T external magnetic field. Both coils have the same area and are oriented at right angles to the field. Which coil will have a greater emf induced in it?
A) coil A B) coil B C) It is impossible to know without more information about the fields.
In which system is heat usually transferred from the cooler part to the warmer part?
a. a stove as it heats up water b. a refrigerator that is running c. an electric fan that is running d. none of the above, because it is impossible to transfer heat in this manner