Introductory Forces and Gravitational Force (Hardest)
What does the Law of Universal Gravitation claim?
Answers may vary.
Attraction proportionally grows according to mass; attraction is equal between subjects; gravitational force grows to infinity and decreases as distance increases.
What are the two types of friction?
a. static and kinetic friction
b. normal and universal friction
c. gravitational and electromagnetic friction
d. constant and instantaneous friction
(Multiple-choice question)
A.
What is the relation of momentum and impulse? Are they proportional?
Answers may vary.
Yes. Momentum is mass in motion. Impulse is the cause to a change in momentum, or a force applied to an object over a period of time.
What is mechanical energy (ME) in a system consisted of?
Potential energy (PE) and kinetic energy (KE).
What is efficiency in the context of work and machines?
Answers may vary.
Efficiency is the measurement of percentage of work input a machine converts to successful work input.
Vectors are arrows representing pressure and force in free body diagrams. What is their representation of an object when it is on the ground?
a. 30° steeper
b. equal
c. free body diagrams are not applicable in that situation
d. exerted force is not represented, only inverted force
(Multiple-choice question)
B.
Note: Be assured, there is no such thing as inverted force:]
What are the SI units for the following?
(A) Distance (B) Displacement (C) Speed (D)Velocity
Distance: meters typically; km if large; cm if small
Displacement: meters
Speed: m/s
Velocity: m/s
What does the Law of Conservation of Momentum claim?
Answers may vary.
The Law of Conservation of Momentum states momentum is conserved in systems provided there is no net external force, and that in an isolated system the momentum "lost" by one object is "gained" by the other object.
Identify the two forms of potential energy and explain their association.
Answers may vary.
Potential energy consists of two types: elastic potential and gravitational potential energy. Elastic PE is potential energy associated with objects that can be stretched or compressed, whereas gravitational PE is potential energy associated with height of an object, in relation to gravity.
What is a compound machine? Explain its nature.
Answers may vary.
A compound machine is a combination of two or more simple machines, possibly including a: lever, pulley, wheel, axle, wedge, or screw.
What is the difference between contact and at-a-distance forces? Please give one example of each.
Answers may vary.
Contact forces act upon the target through collision and direct contact.
Examples: normal, applied, frictional, spring, tension, air resistance forces
At a Distance Forces act upon targets without direct contact.
Examples: gravitational, electric, magnetic forces
Why is acceleration m/s^2? Because:
a. acceleration is time Speed takes up
b. acceleration proportionally relates displacement to velocity
c. Galileo first defined acceleration incorrectly, and was corrected by Newton in the 15th century
d. acceleration is equal to velocity's taken time
(Multiple-choice question)
D.
P.S. If C was chosen, you probably should review history. Newton was born in 1643:]
Out of elastic and inelastic collisions, which statement is true?
a. total momentum is only conserved in inelastic collisions.
b. potential energy is lost as heat/sound in inelastic collisions.
c. total momentum is conserved in elastic and inelastic collisions.
d. kinetic energy is lost as heat/sound in elastic collisions.
(Multiple-choice question)
C.
What happens to potential and kinetic energy as mass increases?
a. potential energy increases.
b. both potential and kinetic energy increases.
c. kinetic energy decreases.
d. both potential and kinetic energy converts into thermal energy.
(Multiple-choice question)
B.
Bob is 50kg. He pushes against a wall at an acceleration rate of 40 m/s^2, with a speed of 5 m/s and 30 seconds. What is his work?
a. 30,000
b. 0
c. 5,000
d. -30,000
(Multiple-choice question)
B.
Bob's subject of work, or the wall, does not move. Thus, work is cancelled.
Remember: No motion = No work
A meteor drops on Earth. What are contact forces and non-contact forces affecting it?
Answers may vary.
CF: Normal force; Applied force from Earth to the meteor; Air Resistance force as it is in motion in the air; Frictional force as it crashes onto Earth
ADF: Gravitational force from Earth; Electric force from positive and negative ions and electromagnetic force; Magnetic force from electromagnetic forces and Earth's magnetic field
Define terminal velocity and its difference from usual velocity or instantaneous velocity (deltaV/ differentialV)
Answers may vary.
Terminal velocity is the constant speed a freefalling object eventually reaches through the air. 'Usual' velocity is the rate of change of distance to time. Instantaneous velocity is the rate of change of an object's position at a specific moment in time.
True or False: Momentum is a vector quantity.
True or False: Impulse is a vector quantity.
(Multiple-choice question)
(1) True.
(2) True.
What happens to potential energy as an object decreases in height and increases in acceleration? (Surface is not frictionless.)
a. potential energy becomes thermal energy
b. kinetic energy becomes gravitational energy
c. kinetic energy becomes thermal energy
d. potential energy becomes kinetic energy
(Multiple-choice question)
D.
No matter of friction, potential energy becomes kinetic energy through motion. Parentheses were to trick.
Which three are simple machines?
a. screw
b. rasp
c. chisel
d. pulley
e. bolt
f. lever
(Multiple-choice question)
A. D. F.
Screw. Pulley. Lever.
Name the four fundamental forces.
a. gravitational force, strong force, weak force, and electromagnetic force.
b. gravitational force, applied force, frictional force, and electromagnetic force.
c. gravitational force, air resistance force, electromagnetic force, and normal force.
d. gravitational force, normal force, applied force, and contact force.
(Multiple-choice question)
A.
Explain the coefficient of friction. Requirements: Unit, Definition, Nature (what it depends on), difference between the two types of friction, how to represent it, and how to calculate it.
Answers may vary.
The coefficient of friction is a value to measure the amount of friction present which is between 1.0 and 0.0. It is unitless (trick question). It is represented by μ (micrometers). μs is the coefficient of static friction whereas μk is the coefficient of kinetic friction. Its formula is μ = Ff/ Fn.
No Question
Physics B4
No Question
Physics B4
Differentiate between Ideal Mechanical Advantage (IMA) and Actual Mechanical Advantage (AMA).
Answers may vary.
Ideal Mechanical Advantage (IMA) is the maximum energy a machine could possibly input, in a hypothetical situation which assumes friction does not cause loss of energy. Actual Mechanical Advantage (AMA) is the actual energy a machine could possibly input, measured in the real world and accounting for energy losses to friction and etc.
(AMA) = Output Force/ Input Force (just a reminder)