PHYSICS 1L03 Chapter Notes - Chapter 4: Apparent Weight, Dynamic Equilibrium, Inertial Frame Of Reference

42 views4 pages

harlequinyellowjacket156

21 Mar 2018

School

Department

Course

Professor

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

Force is a means of describing an interaction between two objects: is the cause of acceleration. Newton"s first law: fnet = 0 = constant. A free body diagram is a drawing that consists of all forces that act on the system of interest. No other physical features of the system are included, such as it"s velocity or acceleration. A coordinate system and labels for angles are often added. An object at rest or in motion with constant velocity remains in its state unless acted upon by a net force (otherwise it"s 0: aka law of inertia. Mass and inertia: large objects have less of a tendency to change velocity than lighter ones, inertia, tendency of opposing a change in the velocity of an object. Inertial reference frame: the reference frame in which newton"s first law is valid, all frames that are stationary or have a uniform motion are inertial frames, all accelerated frames of reference are non-inertial.

Related Questions

1. Which of the following describes an object with a non-zero netforce acting on it? Choose all that apply.
The moped accelerated while making a left turn.
The motorcycle traveled at a constant speed while making au-turn.
The truck slowed down while making a right turn.
The spaceship traveled at a constant speed in a straightline.
The car sped up from 50 mph to 65 mph while moving in a straightline.

2. If you observe that an object is accelerating, what should youconclude?
A non-zero net force is acting on it. Only forces causeacceleration. As such, if an object is accelerating it must bebecause a non-zero net force is acting on it.
It must be in free fall.
It must be changing direction. Acceleration is a vector and vectorshave both magnitude and direction. Thus if an object isaccelerating it must be changing direction.
The forces acting on the object must be greater than the forces theobject is exerting.
It must be speeding up. If an object is accelerating that means itis speeding up.

3. Which of the following are true according to Newton's 2nd Law?Choose all that apply.

If the acceleration is zero, then the net force is zero.
If you apply the same force to 2 objects, the one with more masswill have a greater acceleration.
If you apply the same force to 2 objects, the one with less masswill have a greater acceleration.
If two objects have the same acceleration, the one with less masswill have a larger net force exerted on it.
If two objects have the same acceleration, the one with more masswill have a larger net force exerted on it.
The larger the net force on an object is, the larger theacceleration.
The larger the net force on an object is, the smaller theacceleration.

4. A box is on the Moon. The box weighs 152 lb and is in free fall.How much force is the box exerting on the Moon and in whatdirection?

lb
Up
Down
Right
North
East
West
Left
South

5. Which of the following are the correct units for mass? Chooseall that apply.
slugs
u
kgÂ·m/s2
g
N
m/s2
oz
lb

6. If an object is traveling in a circle, which of the followingmust be TRUE? Choose all that apply.
The object is slowing down.
The object is speeding up.
The object has a net force acting on it.
The object has a constant velocity.
The object is accelerating.

A Simple Atwood Machine consists of two masses m1 and m1 that are connected by a string wound over a pulley, as seen in the figure below. m2 is larger than m1. On a piece of paper, draw two free body diagrams; one for each of the masses, showing all forces acting on each mass. Then answer the following questions. (a) Based on your free body diagram, identify the forces acting on the mass m1. Select all that apply. (m1+m2)a m1g FN m1a (m1+m2)g m2a f m2g T (b) Using the direction rosette indicate the direction for each of the forces acting on m1 that you identified in part (a). If any of the forces listed below is not applicable, enter NA. m1a= m2a= m1g= m2g= (m1+m2)a= (m1+m2)g= f= T= FN= (c) Based on your free body diagram, identify the forces acting on the mass m2. Select all that apply. T (m1+m2)g m2g m1g (m1+m2)a m1a m2a f FN (d) Using the direction rosette indicate the direction for each of the forces acting on m2 that you identified in part (c). If any of the forces listed below is not applicable, enter NA. m1a= m2a= m1g= m2g= (m1+m2)a= (m1+m2)g= f= T= FN= (e) Write Newton's Second Law equation (in the form Fnet = ma) for m1 in the y-direction. Use the first answer box for the left hand side (LHS) of the equation and the second answer box for the right hand side (RHS) of the equation. It is important to use the correct signs for each of the forces. Motion in the upward direction is positive and motion in the downward direction is negative. (Use m1, g, a, and T as appropriate.) LHS = RHS = (f) Write Newton's Second Law equation (in the form Fnet = ma) for m2 in the y-direction. Use the first answer box for the left hand side (LHS) of the equation and the second answer box for the right hand side (RHS) of the equation. It is important to use the correct signs for each of the forces. Motion in the upward direction is positive and motion in the downward direction is negative.(Use m2, g, a, and T as appropriate.) LHS = RHS = (g) Use your answers from parts (e) and (f) to get an expression for the magnitude of the tension T. (Use m1, m2, and g as appropriate.) magnitude of T = (h) Use your answers from parts (e), (f), and (g) to find the magnitude of a, the acceleration of the system. (Use m1, m2, and g as appropriate.) magnitude of a = (i) In what direction will each mass accelerate. For mass m1: For mass m2: (j) Suppose m1 = 7 kg and m2 = 11 kg. What is the tension in the string? T = (k) Suppose m1 = 7 kg and m2 = 11 kg. What is the value of the acceleration? a = (l) Suppose that m2 starts from rest at a height of 5 m. Use the Kinematic Equations to determine how long it takes for m2 to hit the ground.

a.) A hockey puck is observed to be sliding along a flatfrictionless surface at a speed of 4 cm/min. There is no net forceacting on the puck. Assuming it doesn't smash into anything, howfast will the puck be going 17 min later?
cm/min

b.) An object is accelerating. Which one of the followingstatements is true?
The object must be speeding up.
Gravity must be causing the object to accelerate.
The object must be changing directions.
The object must be slowing down.
There is a net force acting on the object.

c.) A 100 kg block weighs 220 lb on Earth. If the block weretransported to a planetary body that had a smaller free fallacceleration (as compared to Earth), which one of the followingwould be true?
The block would have the same weight and a smaller mass.
The block would have the same mass and a bigger weight.
The block would have the same mass and the same weight.
The block would have the same weight and a bigger mass.
The block would have the same mass and a smaller weight.
d.) What does it mean (in physics) to say that a quantity isconserved?
It means that the quantity is not being used.
It means the total amount is zero.
It means the total amount never changes.
It means it's being saved up.

e.) At a certain point in time, the total energy of a closed systemis observed to be 176 J. Which one of the following statements istrue?
Three hours later the energy of the system is 352 J.
Four hours later the energy of the system is 88 J.
All of the energy must be kinetic if the objects are moving.
Twelve hours later the energy of the system is 176 J.
Some of the energy must be potential.

g.) Which of the following statements are impossible? Choose allthat apply.
The parked truck had 8770 J of KE.
The scooter had 0 J of KE and 0 kgÂ·m/s of momentum.
A ball moving in a circle had 0 N of net force acting on it.
A box had an acceleration of 0 m/s2 while a net force of 311 Nacted on it.
Jack exerted 18 N of force due east on a cart. As a direct result,the cart exerted 18 N of force due west upon Jack.
A toothpick exerts a smaller gravitational force upon the Moon thanthe Moon exerts upon it.

a.) Two balls make up a closed system. Ball A has 701 J of energyand ball B has 78 J. After they collide, ball A has 665 J. How muchenergy does ball B have after they collide?
J

b.) An asteroid and a comet collide head on. Prior to thecollision, the asteroid has a momentum of 700,000 kgÂ·m/s up and thecomet has a momentum of 800,000 kgÂ·m/s down. After the collisionthe asteroid has a momentum of 750,000 kgÂ·m/s down. After thecollision, what is the comet's momentum?
kgÂ·m/s
North
South
East
West
Up
Down
Left
Right
No direction because the comet has stopped

c.) How much does a 28 kg object weigh on Moon? Please feel free toreference the Solar System Data table located at the beginning ofUnit II.
______N

d.) A 660 N net force acts on a 42 kg object. Determine theobject's acceleration.
_____m/s2

e.) Calculate the gravitational force between a 657 kg object(resting on Earth) and the Moon. The mass of the Moon is 7.347Ã1022kg and the distance between the object & the Moon is 3.844Ã108m.
____N

PHYSICS 1L03 Chapter Notes - Chapter 4: Apparent Weight, Dynamic Equilibrium, Inertial Frame Of Reference

Document Summary

Get access

Related textbook solutions

Physics: Principles with Applications

Related Documents

PHYSICS 1L03 Lecture Notes - Coordinate System

PHYSICS 1L03 Chapter Notes - Chapter 5: Conservation Law, Momentum, Net Force

PHYSICS 1L03 Study Guide - Free Body Diagram, Net Force, Contact Force

Related Questions