Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: THEend8_
Midterm Review
Motion:
1. What is the definition of acceleration?
2. A car moves with a steady speed of 84 km/h for 45 min, then 96 km/h for 20 min.
a. What was the total distance travelled during the whole trip?
b. What is its average speed for the whole trip?
3. The figure below shows a speed-time graph for a vehicle.
a. What was the acceleration of the vehicle?
b. What was the average speed of the vehicle during its 5.00 s trip?
c. What distance did the vehicle travel during the 5.00 s?
d. Write a specific equation for this graph.
4. A high-powered racing car accelerates from rest at a rate of 7.0 m/s2. How fast will it be moving after 10.0 s? Convert this speed to km/h.
5. A child on a toboggan slides down a snowy hill, accelerating uniformly at 2.8 m/s2. When the toboggan passes the first observer, it is travelling with a speed of 1.4 m/s. How fast will it be moving when it passes a second observer, who is 2.5 m downhill from the first observer?
6. A space vehicle is orbiting the earth at a speed of 7.58 x 103 m/s. In preparation for a return to earth, it fires retro-rockets, which provide a negative acceleration of 78.4 m/s2. Ignoring any change in altitude that might occur, how long will it take the vehicle to slow down to 1.52 x 103 m/s?
7. A very frustrated physics student drops a physics textbook off the top of the CN tower. If the tower is 5.3 x 102 m high, how long will the book take to reach the ground, assuming there is negligible air resistance?
8. If an electron inside a TV tube accelerates in a space of 5.0 cm from rest to 1/10 c, (where c is the speed of light, which is 3.0 x 108 m/s), what is its acceleration?
9. Snoopy is taking off in his WW I biplane. He coasts down the runway at a speed of 40.0 m/s, then accelerates for 5.2 s at a rate of 1/2 g , where g is the acceleration due to gravity (9.81 m/s2). How fast is the plane moving after the 5.2 s?
10. A glider on an air track is made to accelerate uniformly by tilting the track at a slight angle. The distance travelled by the glider was measured at the end of each 0.10 s interval, and the following data was gathered:
|
Distance d (cm) |
0 |
0.025 |
0.100 |
0.225 |
0.400 |
0.625 |
|
Time t (s) |
0 |
0.100 |
0.200 |
0.300 |
0.400 |
0.500 |
|
|
|
|
|
|
|
|
a. Label and plot distance d (on the Y-axis) vs. time t (on the X-axis) on the first grid below.
b. If a d vs t graph is linear, it means there is no and the equation to
represent the relation would be d = .
c. If a d vs t graph is NOT linear, it often means that there is and the
equation to represent the relation would be d = , and with vo = 0, it would simplify to be d = .
d. Let's try to linearize this data by adding a new row to the table above, then plot a second graph with distance d on the Y-axis and t 2 on the X-axis. Is it linear now?
e. Use the slope of your second graph and your equation to figure out the acceleration of the glider on the air track.
11. A motocross rider is coasting at a speed of 2.00 m/s. He then decides to accelerate his bike at a rate of 3.00 m/s2 for a distance of 100.0 m.
a. How fast is the bike moving, in m/s, at the end of the 100.0 m stretch?
b. Convert your answer to (a) from m/s to km/h.
12. A mountain bike rider, after coming down a steep hill, loses control of her bike while moving with a speed of 5.00 m/s. Fortunately, she collides with a haystack, which brings her to rest in a distance of 0.625 m. What was the acceleration of the bike and rider while colliding with the haystack?
13. A lady walking her dog travels 200 m North, then 400 m West, then 500 m South.
a. What was the total distance she travelled?
b. What was the magnitude of her displacement for the entire trip?
Projectiles and Relative Velocity:
14. An airplane is heading directly north at 120 m/s, but a wind from the west is giving the plane a
velocity component of 20.0 m/s relative to the air. What is the resultant velocity of the plane relative to the ground? Give the direction of the plane in ‘degrees east of north’ .
15. A boat is crossing a river. The boat's velocity is 5.6 m/s (in a direction directly across the stream).
The flowing water carries the boat downstream at a rate such that the resultant velocity of the boat is 6.5 m/s. What is the velocity of the water in the river? Use a scale diagram or trigonometry to determine the angle the boat's resultant velocity makes with its intended velocity, which was directly across the stream.
16. If a boat travels 8.0 m/s relative to the water, the river water speed is 3.0 m/s, and the boat operator must land his boat directly opposite to the point from which he embarks on his trip, in what direction must he aim his boat throughout the trip? How long will it take to cross the 100m wide river?
17. A golf shot is at 60o above the horizontal, if its speed is 27m/s find its time in air, range and maximum height.
18. A stone is thrown horizontally at 5 m/s off a 78.4 m high cliff. How long does it take to reach the ground, how far is it from the base of the cliff and what are its final velocities in the horizontal and vertical directions?
19. How would the answers to #18 change if the horizontal velocity was increased?
20. How would the answers to #18 change if the height of the cliff were increased?
21. A daredevil BMX rider runs his bike off a cliff with a horizontal velocity of 4.5 m/s, and lands in the water 12 m from the base of the cliff.
a. How long does it take the rider to hit the water? (ans: 2.7 s )
b. How high is the cliff? (ans: 35 m)
22. As part of a NASA experiment, golfer Tiger Woods drives a golf ball on the moon, where g =
1.60 m/s2. He ‘launches’ a golf ball with a speed of 285 km/h, at an angle of 42o with the horizontal. What horizontal distance will his drive travel before landing back on the surface of the moon. Ignore the curvature of the moon (ans: 3.9 kilometres! )
23. A projectile is launched with a speed of 128 m/s, at an angle of 60o with the horizontal.
a. After 2.0 s, what is the vertical component of the projectile’s velocity? (ans: 91 m/s)
b. After 2.0 s, what is the speed of the projectile? (ans: 112 m/s)
24. A tank shell is fired at a speed of 300 m/s at an angle of 30° above the horizontal.
a. What is the maximum altitude reached by the shell? (ans: 1.1 km)
b. How long is the shell in the air? (ans: 31 s)
c. Calculate the range of the shell. (ans: 7.95 km)
25. An arrow is shot from the top of a castle wall at a speed of 15 m/s at an angle of 15° below the horizontal, and hits the ground with a speed of 28 m/s. Calculate the height of the wall. (ans: 28.5m)
26. A boys uses a slingshot to fire a pebble at 25 m/s at an angle of 40° above the horizontal. Two seconds later the pebble just passes over the top of a nearby tree.
a. Calculate the height of the tree. (ans: 12.5m)
b. Determine the velocity of the pebble as it passes over the top of the tree. (ans: 19.5 m/s @ 10.4。below the horizontal)
27. Golfer Arnold Hacker requires three putts from position A to put his ball in the hole. His first
putt, from A to B, travels 8.0 m south. His second putt, from B to C, travels 1.2 m southwest. His third putt, from C to the hole at D, travels 0.50 m northwest. What would be the magnitude and direction of the single putt that would have put the ball into the hole, from A to D? (ans: One putt would travel 8.0o W of S, a displacement of 8.6 m)
28. The current in a river is such that the water flows toward the north at 2.1 m/s. An alligator swims toward the west, at 2.4 m/s relative to the water. What is the resultant direction of travel of the alligator? (ans: 49o W of N)
29. An airplane heads due west with an airspeed of 84 m/s. Because of a wind blowing due north, the speed of the airplane relative to the ground is 98 m/s. What is the wind speed? (ans: 50 m/s toward north)
Forces:
31. A student added masses to the end of a hanging spring, then measured the amount of extension (stretch) caused by the force of gravity on each mass. The following readings were obtained:
|
Mass (kg) |
0.200 |
0.400 |
0.600 |
0.800 |
1.000 |
|
Force of Gravity (N) |
1.96 |
3.92 |
5.88 |
7.84 |
9.80 |
|
Extension (cm) |
0.47 |
0.93 |
1.41 |
1.89 |
2.35 |
a. Label and plot a graph with Force of Gravity (Fg) on the Y-axis and Extension (x) on the X- axis.
b. Determine the slope of the graph (in appropriate units), and write an equation describing how the force of gravity varies with the extension.
c. Use both your graph and your equation to figure out the force of gravity that would stretch the spring 1.50 cm.
d. Use both your graph and your equation to figure out how much stretch would occur in the spring when the force of gravity is 6.50 N.
32. To slide a metal puck across a greased sheet of metal at constant speed requires a force of 0.525 N. If the force of gravity on the puck is 5.00 N, what is the coefficient of friction between the puck and the greased metal?
33. The force of gravity on a wooden crate is 560 N. It can be pushed along a certain floor at steady speed if a horizontal force of 224 N is applied to it. How much horizontal force will be needed to move a stack of two crates at the same steady speed? What force will be needed if the two crates are not stacked but tied to one another side by side?
34. What is the resultant force if these three forces act on the same point? 100.0 N to the north; 50.0 N to the east; and 220.0 N to the south.
35. Three ants are struggling to move the remains of a bee. (Three uncles refuse to help.) One ant pushes north with a force of 35 mN (millinewtons). A second ant pushes east with a force of 12 mN. The third ant, an uncooperative little bug, exerts a force that exactly cancels the effects of the other two. What is the magnitude of the force exerted by the third ant, and in what direction does it push?
36. What is the force of gravity on a 1.0 g mass here on earth, where the gravitational field strength is
9.8 N/kg?
37. What is the gravitational field strength in a location where the force of gravity on a 14.67 kg mass is 143.62 N?
38. The force of gravity on a 5.0 kg mass on Mars is 18.05 N. At what rate will the mass accelerate toward Mars if it is in free fall? What fraction is this acceleration of what the same mass would have in free fall on earth?
39. What unbalanced force is needed to accelerate a 5.0 kg cart at 5.0 m/s2?
40. A net force of 7.5 x 104 N acts on a spacecraft of mass 3.0 x 104 kg.
(a) At what rate will the spacecraft accelerate?
(b) Assuming constant acceleration is maintained, how fast will the spacecraft be moving after 25 s, if its initial speed was 5.0 x 103 m/s?
41. A model rocket has a mass of 0.12 kg. It accelerates vertically to 60.0 m/s in 1.2 s.
a. What is its average acceleration?
b. What is the unbalanced force on the rocket?
c. If the force of gravity on the rocket is 1.2 N, what is the total thrust of its engine?
42. A fully loaded military rocket has a mass of 3.0 x 106 kg, and the force of gravity on it at ground level is 2.9 x 107 N.
a. At what rate will the rocket accelerate during lift-off, if the engines provide a thrust of 3.3 x 107 N?
b. Why will this acceleration not remain constant?
43. A boy and his skateboard have a combined mass of 60.0 kg. After an initial shove, the boy starts coasting at 5.5 m/s along a level driveway. Friction brings him to rest in 5.0 s. If the combined force of gravity on the boy and skateboard is 5.9 x 102 N, what is the average coefficient of (rolling) friction between the driveway and the skateboard wheels?
- 经济Economics
- 金融Finance
- 会计Accounting
- 工商管理Business Management
- 计算机computer science
- 商业分析business analysis
- 法律Law
- 管理Management
- 市场营销Marketing
- 哲学Philosophy
- 心理学Psychology
- 物理Physical
- 统计学statistics
- 电气工程electric engineering
- 化学chemistry
- 生物biology
- 数学mathematics
- 语言学linguistics
- 土木工程civil engineering
- 工程力学engineering mechanics
- 艺术art
PROFESSIONAL HELP!
在线咨询
立即下单
Wechat：THEend8_ 
Email：