3. If the mass of Earth increased, with no change in radius, your weight would _____.
a) Stay the same
c) Increase also
4. The decimal equivalent of 10 to the negative 2 is
5. Which of the following is true?
a) Weight is the gravitational force an object experiences due to its mass.
b) Weight is the gravitational force an object experience due to its mass.
c) The weight of an object on Earth is greater than the weight of the same object on the surface on the moon, but the object's mass stays the same.
d) All of the above
6. A 4.0-kg ball has a momentum of 20.0 kg m/s. What is the ball's speed?
a) 0.2 m/s
b) 5.0 m/s
c) 20.0 m/s
d) 80.0 m/s
e) None of the above
7. You are asked to find the area of a room that is 4.56 m long and 5.668 m wide. How many significant figures should you show in your answer?
8. The number 56,780,000,000 would be written in scientific notation as _______ x ___________.
9. You are asked to find the volume of a cube that is 2.5 cm high, 2.65 cm wide, and 3.456 cm long. How many significant figures should you show in your answer?
10. In the universal gravitation equation, the constant G has a value of 6.67 x 10 ^-11 N x m^2/kg^2. Find the force a 4 kg ball exerts on a 2 kg ball if the distance between their centers is 4 m.
11. The number 0.0034 would be written as 3.4 times _________________ in scientific notation.
12. What is the average momentum of a 50-kg skateboarder who covers 400 m in 50 seconds?
13. Calculate the force of gravity between Earth (mass = 6.0 x 10^24) and Mars (mass = 6.0 x 10^23kg) when they are at their closest distance from each other 5.6 x 10 to the power of 7 km. Hint: Don't forget to convert the km into m first before you solve.
14. In scientific notation, the number 46,500,000 would be written ________________.
15. A large truck loaded with scrap steel weighs 14 metric tons and is traveling north on the interstate heading for Chicago . It has been averaging 48 km/h for the journey and has traveled over 1450 km so far. It has just stopped to refuel. What is its current momentum?
16. The number 0.0009234 would be written in scientific notation as __________ x _________.
17. Discuss how the force of gravity between two masses depends on the size of their masses and the distance between them. Give a numerical example.
18. What does it mean to say that momentum is conserved? Give at least two examples where momentum is conserved.
Rank each of the following sets of scenarios in order of the quantity or property involved. List them from left to right. If scenarios have equal rankings, then separate them with an equal sign. (e.g., A = B)
19. The balls have different masses and speeds.
A. Mass=1.0kg and speed=9.0 m/s
B. Mass=1.2kg and speed=8.5 m/s
C. Mass=0.8kg and speed=12.0 m/s
D. Mass=5.0kg and speed=2.0 m/s
Rank the following from greatest to least.
b. The impulse needed to stop them
20. Below are before and after pictures of a car's speed. The mass of the car doesn't change.
A. Before=10 m/s, After=20 m/s
B. Before=20 m/s, After=15 m/s
C. Before=0 m/s, After=10 m/s
D. Before=15m/s, after=15 m/s
Rank the following from greatest to least.
a. The magnitude of momentum change.
b. The magnitude of impulse producing the momentum change.
21. The mass and speed of three vehicles are shown below.
A. Mass=800kg and speed=1.0m/s
B. Mass=1000kg and speed=2.0m/s
C. Mass=90kg and speed=8.0m/s
a. Rank the vehicles by momentum from greatest to least.
b. Rank the vehicles by kinetic energy from greatest least.
22. Consider these four situations.
A. 3-kg ball at rest atop a 5-m-tall hill
B. A 4-kg ball at rest atop a 5-m-tall hill
C. A 3-kg ball moving at 2 m/s atop 5-m-tall hill
D. A 4-kg ball moving at 2 m/s at ground level
a. Rank from greatest to least the potential energy of each ball.
b. Rank from greatest to least the kinetic energy of each ball.
c. Rank from greatest to least the total energy of each ball.
23. What is the efficiency of her body when a cyclist expends 1000 W of power to deliver mechanical energy to the bicycle at the rate of 100 W?
24. In what sense are our bodies machines?
25. What is the ultimate source of the energy derived from the burning of fossil fuels, from dams, and from windmills?
26. What is the ultimate source of geothermal energy?
27. Can we correctly say that a new source of energy is hydrogen? Why or why not?
This posting contains the solution to the given problems.