Download physics: semester 1 final review

PHYSICS: SEMESTER 1 FINAL REVIEW
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1. Explain the difference between velocity and acceleration
2. Sonny drives from Alameda to Las Vegas, covering 750 miles in 15 hours. What is his
average speed?
3. Mary's sports car accelerates from 20 km/hr to 100 km/hr in 5.0 seconds. What is the
average acceleration?
4. An airplane flying east at 200 km/hr encounters a wind from the South also of 200 km/hr.
What is the airplane's speed over the ground?
5. Explain and illustrate what is meant by the components of a vector.
6. Two students pull on a third. One student pulls with 300 N; the other with 800 N. What
are the largest and smallest net forces possible and under what conditions will they exist?
6a. Draw a diagram illustrating the two forces pulling at an angle of 30 degrees to each other
and indicate how you would find the resultant force.
7. A toy rocket is launched upward with a speed of 100 m/s. (assume g = 10 m/s/s)
(a) after three seconds, what will be the speed of the rocket?
(b) what will be the velocity of the rocket at the top of its path?
(c) what will be the acceleration of the rocket at the top of its path?
(d) Neglecting air resistance what will be the speed of the rocket when it returns tpo
the ground?
Suppose the rocket were launched at a 45 degree angle instead of straight up.
(e) At what point in its path will the rocket's speed be minimum?
(f) What will its speed be at this point?
Suppose the rocket were launched instead at 40 degrees above the horizontal.
7 (g) At what other angle(neglecting air resistance) would it travel the same horizontal
distance?
8. Complete the table of standard units(in some cases more than one answer is possible):
Quantity velocity
Unit
acceleration force
work
power
momentum
Vector or
scalar?
9. Which of these (circle one) is the formula for linear momentum mv/2 mv 1/2mv2 mv2
10. Rex, the German Shepard, runs at 8 m/s. His mass is 25 kg. What is his momentum?
11. Rama, another Shepard, mass 20 kg, runs directly at Rex. Her speed is 10 m/s. They
collide inelastically(without getting hurt). Describe what happens:
12. A 200 gram glider on an air track traveling to the right at 0.10 m/s collides inelastically
with another glider of the same mass at rest. Describe what happens:
13. A 5 kg fish swimming to the right at 1 m/s swallows a one kg goldfish swimming to the
left at 1 m/s. Exactly what happens (what is final velocity?)
14. A rock drops from a high tower for exactly four seconds and hits the ground. Neglect air
resistance. Assume g = 10 m/s/s.
(a) what is the speed of the rock when it hits the ground?
(b) What is the height of the tower?
15. Toni throws a 0.20 Kg ball with an acceleration of 10 m/s/s.
(a) What force did she exert on the ball?
(b) What force did the ball exert on her?
16. A powerful rocket has a thrust of 2.4 million Newtons and a mass of 200,000 kg. What
would be its horizontal acceleration?
What would be its vertical acceleration?
17. (Complete): Impulse equals change of ________________.
18. (Complete): Impulse equal force times _____________
19. A tennis player applies an average 10N force to a 0.05 Kg ball that flies off at 40 m/s.
For what time was the racket in contact with the ball?
20. In terms of impulse, what is the purpose of a car's padded dashboard?
21. A speeding bullet has a mass of 10 grams. It travels at 500 m/s. What is its kinetic
energy?
The gun that shot the bullet has a mass of one kg. What is its recoil speed? What is its
kinetic energy after recoiling? (assume it is on the end of a long string rather than being held
by a person)
22. At a height of 100 meters above the ground, what would be the potential energy of a 2.5
kg brick?
How much work is required to raise the brick from the ground to 100 meters?
If the brick falls, what will be its kinetic energy just before it hits the ground?
23. Explain the Law of Conservation of Energy:
24. What happens to the energy of the brick when it hits the ground?
25. If the brick is pulled along the ground, what is the direction of the friction force on the
brick?
26. If the brick is pulled at a steady speed of 1.5 m/s, what is the magnitude of the friction
force on the brick?
What is the net force on the brick?
Is the brick in equilibrium in this case?
27. What does Newton's Law of Inertia have to say about masses at rest or moving with
constant velocity?
28. The earth circles the sun at nearly steady speed. Does it have constant velocity?
Explain. Describe its acceleration, if any.
29. What is mechanical power?
30. Mary, whose mass is 60 Kg, climbs a 20 meter hill in 60 seconds.
(a) how much work does she do?
(b) what average power is needed for her to do this?
31. What work is done, if any, to keep the Earth in a nearly circular orbit around the sun? Is
any power required?
32. Two large masses are at a certain distance from each other. What will happen to the
gravitational force of attraction between them if the distance is doubled? If the distance
is halved? What is both masses are doubled but the distance stays the same?
33. Meg weighs 200 N on Planet X. Planet Y has half the radius of Planet X but the same
mass. What would Meg weigh on Planet Y?
34. A marble is released from the top of a U shaped track. Realistically, how far up the other
side of the track will it go?
35. Sketch graphs of velocity, acceleration, and position versus time for a falling ball. Be
sure to label the axes:
36. What was it about the moon that convinced Newton that the moon was accelerating?
37. Can an object's speed be increased by applying a force to it perpendicular to its direction
of motion? Explain.
38. What is constantly changing for a satellite in a circular orbit?
39. In terms of forces, what is required to keep an object moving in a circle?
40. The earth exerts a huge gravitational force on the moon. Why doesn't the moon fall into
the Earth?
41. Explain Newton's Third Law of motion in your own words and give an example:
42. A steady force is used to accelerate a sled over the ice. Suddenly a mass equal to that of
the sled is placed neatly on the sled. What happens to the acceleration of the sled?
What Law of Newton is involved in the above situation?
Write this Law as a mathematical equation:
What would happen to the acceleration of the sled if the force pushing it were tripled?
43. An unbalanced force on an object produces a change in its _________________ (more
than one answer possible)
44. Two balls collide. What two basic conservation laws of physics apply?
If we see one ball stop, and the other ball, previously at rest, fly off with the speed of the
initially moving ball what can we conclude about the balls and the collision?
45. How is momentum different than energy? (at least two differences)
46. What two forms of energy transfer are possible between systems?
47. In terms of heat flow and work, describe how a heat engine works:
48. What is the difference between internal energy and heat?
49. What is the relationship between the speed of molecules and the temperature of a system.
50. What is the difference between the thermal, or internal energy, of a flying baseball, and
its kinetic energy?
51. If an insulated tank of water is violently stirred what will happen to its temperature?
Why?
52. What is specific heat capacity? Explain, in terms of specific heat, how metals and
water are different when you heat them.
53. In each cycle, 2000 J of heat flows into an engine and 400 J of mechanical work is done.
a. What is the efficiency of the engine?
b. How much heat is exhausted from (wasted by) the engine per cycle?
54. If 100 J of heat flows into a sample of ideal gas and 50 J of work is done ON the gas,
what will be the change of internal energy? What Law of Thermodynamics tell us this?
55. What does the Second Law of Thermodynamics say about
a. heat flowing between hot and cold objects?
b. heat engines and refrigerators?
c. entropy?
d. the fate of the Universe
56. In terms of basic physics explain why a student's room does not naturally tend to become
more orderly:
57. Why would physicists be very surprised if all the air molecules in the classroom
accumulated in the top half of the room?