Download Elements of Science Midterm Exam Review Answer Key

Elements of Science Midterm Exam Review
Answer Key
Part 1:
1. The rate of change of velocity is known as ________
2. A ____ force
acceleration
________________ is a push or a pull.
3. Forces on an object that are equal in size and opposite in direction are called _______ forces.
balanced
4. Newton’s First Law, the Law of ______ inertia ___________________, is the tendency of an
object to resist any change in its motion.
5. Newton’s Second Law states that the greater the _____ mass __________ of an object the
greater the amount of force needed to accelerate the object.
6. An object at rest has _____ zero
______________ velocity.
7. The attractive forces between two objects that depends on the masses of the objects and the
distance between them is gravity
8. ____ weight ____________ is the gravitational force exerted on an object’s mass.
9. Mechanical energy is the total amount of __ potential and kinetic energy ________ in a
system
10. Friction converts mechanical energy into _ thermal _______ energy.
11. The ability to cause change is __ energy __________
12. The energy a moving object has because of its motion is kinetic energy
13. The energy stored in an object is potential energy
14. Energy stored by something that can stretch or compress is _ elastic potential energy
15. The energy stored in chemical bonds is _ chemical potential energy ______________
16. The energy stored by objects due to their position above the Earth’s surface is
gravitational potential energy
17. In order for work to be done a force must __ make something move ______________
18. __ power ______________ is the rate at which work is done.
19. A (n) ___ machine _______________ is a device that makes doing work easier.
20. ____ efficiency _____________ is a measure of how much of the work put into a machine is
changed into useful output work by the machine.
21. When a machine is used to do work, the force that is applied to the machine is the
__ input force
______________
22. This type of machine does work with only one movement of the machine. simple
23. A screwdriver being used to open a paint can is an example of this simple
machine. lever
24. A doorknob is an example of this simple machine.
wheel and axle
25. This type of machine is made up of a grooved wheel with a rope, chain or cable running
along its groove. pulley
26. This type of machine consists of a shaft or axle attached to the center of a larger wheel so
that the wheel and axel rotate together. wheel and axle
27. An inclined plane with one or more sloping sides is a (an) wedge
28. The measure of the average kinetic energy of the particle in an object is temperature
29. The sum of the kinetic and potential energy of all of the particle in an object is
thermal energy
30. Thermal energy that flows from something at a higher temperature to something at a lower
temperature is heat
31. The amount of heat that is needed to raise the temperature of 1 kg of some material by 1oC is
specific heat
32. _______________ is the transfer of thermal energy by collisions between particles in matter.
conduction
33._______________ is the transfer of thermal energy in a fluid by the movement of warmer and
cooler fluid from place to place. convection
34. A fluid expands as its temperature increases. As a result its _ density____ decreases.
35. A material in which heat flows slowly is a(n) insulator
36.__ radiation ___________ is the transfer of energy by electromagnetic waves.
Part 2: diagrams and formulas
37. Where would the gravitational potential energy be the highest?
letter B
B
D
C
(the ground)
A
38. The chain on Sam's bike, which has a mass of 400 kg, is broken. Sam is trying to push the bike to his
house, and he makes the bike go 1 m/s/s. How much force is Sam is applying to the bike? You must show
all work and then circle the correct answer
F = MA
F = __400kg__ x __1 m/s/s______
Answer: F =___400N___________ (Be sure to include your units!)
39. A jogger whose mass is 40g is moving at a speed of 2m/s. What is the jogger’s kinetic
energy? You must show all work and then circle the correct answer.
KE=1/2mv2
KE=1/2(_40kg____)( 2m/s___)2
KE=1/2(_40kg____)(_4m/s_____)
Answer: KE=____80 J______________ (Be sure to include your units!)
40. Find the GPE of a coffee mug with a mass of 2 kg on a 1-m high counter top. Gravity is 9.8
m/s/s. You must show all work and then circle the correct answer
GPE = mgh
GPE = (_2kg__)(_9.8 m/s/s___)(_1m____)
Answer: GPE =___19.6 J__________________(be sure to include your units!)
41. A boy has a mass of 10 kg. The acceleration of gravity is 9.8 m/s/s. How many Newtons does
he weigh? You must show all work and then circle the correct answer
W = mg
W = (_10 kg_______)(_9.8 m/s/s________)
Answer: W =____98.0 N_______________(be sure to include your units!)
42. A force of 10 N is exerted on a 45 kg sofa and the sofa is moved 5 m. How much work is
done in moving the sofa? You must show all work and then circle the correct answer
Formula:
W = Fd
W=(__10 N_____) (__5 M_____)
Answer: W =___50 J__________________(be sure to include your units!)
43. What is the acceleration of a cat who is chasing a mouse at 12 m/s and comes to a complete
stop in 2 s? You must show all work and then circle the correct answer
a = Vf - Vi
t
(
0
-
12m/s
)
a =
2s
Answer: a =___- 6 m/s/s_______________(be sure to include your units!)
44. You do 200 Joules of work carrying your backpack up a flight of stairs. If it took 5 s to move
the sofa, what was your power? You must show all work and then circle the correct answer
P=W
t
P = 200J
5s
Answer: Power = __40 W_______________ (Be sure to include your units!)
45. Find the change in thermal energy of a 60 kg marble counter top that warms from 10 0C to 20
0
C if the specific heat of wood is 10 J/kg (C). You must show all work and then circle the correct
answer
Q = m (Tf – Ti) C
Q = __60_kg___ ( _20 0C______ - __10 0C ___ ) ___10 J/kg C______
Q = _60kg_____ ( _10__0C _____ ) ___10 J/kg C ________
Answer: Q =___6000 J______________ (be sure to include your units!)
46. What kind of simple machine is shown in the image below? screw
47. What kind of simple machine being used in the image below? wedge
48. What kind of simple machine being used in the image below? pulley
49. Calculate the net force shown in the vector diagram below. Draw and label the resulting
vector and then circle the correct answer.
10 N
5N
+
=
5N
50. Calculate the net force shown in the vector diagram below. Draw and label the resulting
vector and then circle the correct answer.
10 N
8N
+
18 N
=