Download 8th 2014 midterm

8th 2014 midterm Review
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What is displacement?
Motion means you are changing what?
If you have a point used to locate a thing, what is it called?
Total distance traveled divided by the total time of travel gives you what?
What is shown in this graph?
6) if a ball rolls for 10 seconds and rolls 5 meters, what is its average speed?
7) If an object is at rest, what is its speed?
8) What does acceleration describe?
9) What does instantaneous speed mean?
10) What two things do you need to know to describe velocity?
11) A straight horizontal line on a speed-time graph says what?
12) A car slows down. Is it accelerating?
13) An object is moving at a constant speed. What would a distance-time graph show?
14) Is gravity a contact force or a noncontact force?
15) If an arrow represents a force, what does the length of the arrow show?
16) How is momentum affected by mass?
17) If an object is accelerating, what is it doing?
18) Is friction a force?
19) We walk forward because the ground is doing what?
20) Action and reaction forces are equal, but act in --- directions.
21) Daniel hits a nail with a hammer. What object(s) get a force?l
22) What is p = m x v?
23) How does the combined momentum of two objects before a collision compare to their
combined momentum after a collision?
24) Define balanced forces.
25) What is static friction?
26) I am falling. What upward force is acting on me?
27) If a 3,000-N force give something an acceleration of 30 m/s/s, what is the object’s
mass?
28) State Newton’s 3rd law.
29) What is the unit:
a) of force?
b) of work?
c) for power?
30) What force is the result of using a machine?
31) How does a machine change the type of a force?
32) A carpenter applies 150 N to the end of a crowbar. The force exerted on the board is
600 N. What is the mechanical advantage of the crowbar?
33) A worker applies a force of 25 N to pry open a window that has a resistance force of
500N. What is the mechanical advantage of the crowbar?
34) Find the force needed to lift a 2000N rock, using a jack with a mechanical advantage
of 20.
35) Joe is using a crowbar to remove a tree stump. He applies 2056 J of work to the
crowbar. The output work of the crowbar is 514 J. What is the efficiency of the
crowbar?
36) What is the ideal mechanical advantage of the pulley shown?
37) How do you calculate the mechanical advantage of a wedge?
38) What’s a compound machine?
39) A wheelbarrow is an example of a compound machine that uses a lever and a wheel
and axle. The efficiency of a compound machine is calculated by multiplying the
efficiencies of each simple machine together. Suppose the efficiency of the lever is
96% and the efficiency of the wheel and axle is 93%. What is the efficiency of the
wheelbarrow?
40) Define inclined plane.
41) Define lever
42) What word describes the rate at which work is done?
43) Define mechanical advantage.
44) If you wrap an inclined plane around a cylinder, what do you get?
45) Define compound machine.
46) What is:
a) a measure of the distance an object travels in a unit of time?
b) An object’s distance in a certain direction from a reference point.
c) The rate of change of position in which the same distance is traveled each
second.
d) A change in the velocity during a time interval divided by the time interval
during which the velocity changes.
e) The speed and the direction of a moving object.
f) The total distance traveled divided by the total time taken to travel that distance.
g) The process of changing position.
47) Describe the motion of a car with an acceleration of –2 m/s2.
48) "If no forces are acting on a moving object, it will eventually come to rest." Is this
statement true or false? Discuss your reasons for thinking this way.
49) Scissors are basically two first-class levers. Using what you know about calculating
mechanical advantage for levers, explain why it would be easier to cut something if the
handles were long and the blades were short.
50) A swimmer swims 20 m in 40 s. What is the swimmer’s average speed?
51) You travel 190 km in 2 h. What is your speed in km/h?
52) A car goes from 80 km/h to 20 km/h in 0.5 h. What is the acceleration in km/h2?"
53) A top-fuel dragster accelerates from rest to a velocity of 100 m/s in 8 s. What is the
acceleration?
54) A train traveled 250 kilometers (km) from its starting point in 5 hours (h). If the train
continues at the same average speed for another 4 hours, how far will it have traveled
from its starting point? Show your work.
55) Suppose that the average speed your dog can run is 2 m/s. Remember, average
speed = total distance/total time. How much time will it take your dog to run 120 m?
56) Calculate the force on an object that has a mass of 12 kg and an acceleration of 4
m/s2.
57) How much power is needed to do 1,000 J of work on a box if it takes 50 s to lift it?
58) How much work is done if 500 W of power is used over 2 min?