How long would it take 4.00 × 1020 atoms to decay to 1.00 × 1019 atoms if their half-life was 14.7 years?
A) 58.8 years B) 78.2 years C) 147 years D) 29.4 years
B
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Suppose you heat an oven to 400°F (about 200°C) and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven?
A) The water can transfer heat to your arm more quickly than the air. B) The water has a higher temperature than the oven. C) The molecules in the water are moving faster than the molecules in the oven. D) The oven has a higher temperature than the water.
An airplane is flying through a thundercloud at a height of 2 500 m. (This is a very dangerous thing to do because of updrafts, turbulence, and the possibility of electric discharge.) If there is a charge concentration of +42 C at height 4 000 m within the cloud and ?42 C at height 500 m, what is the magnitude of the electric field E at the aircraft? (ke = 8.99 × 10^9 N·m2/C2)
a. 9.4E+4 N/C b. 1.7E+5 N/C c. 6.2E+4 N/C d. 2.6E+5 N/C e. 1.9E+5 N/C
A small car pushes on a disabled truck, accelerating it slowly forward. Each exerts a force on the other as a result of their contact interaction. Which vehicle exerts the greater force on the other?
A. The car B. The truck C. Both forces have the same magnitude. D. The truck doesn’t exert any force on the car. E. One needs more information to answer.
Given that Earth's actual distance from the Sun varies by less than 3% over the course of a year, why does the diagram look so elliptical?
A) It correctly shows that Earth is closest to the Sun at points A and C and farthest at points B and D. B) The elliptical shape is an effect of perspective, since the diagram shows an almost edge-on view of a nearly circular orbit. C) The shape of the diagram is meaningless and is done only for artistic effect.