PHYA11H3 Chapter 1,2: Chapter 1, 2 notes

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pucecicada571

15 Dec 2016

School

UTSC

Department

Physics and Astrophysics

Course

PHYA11H3

Professor

Salam Tawfiq

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PHYA11H3 Full Course Notes

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Document Summary

The sign of position (x or y) tells us where an object is. The sign of velocity (vx or vy) tells us which direction the object is moving. The sign of acceleration (ax or ay) tells us which way the acceleration vector points, not whether the object is speeding up or slowing down. (see table box 1. 4) An object is speeding up if and only if vx and ax have the same sign. An object is slowing down if and only if vx and ax have opposite signs. An object"s velocity is constant if and only if ax = 0. Interpreting a position graph: look at figure 1. 22a. As the is decreasing as shown by line going down it shows that car was travelling to the left for 30 min as position was decreasing. The straight line shows that the car stops for 10 min as there is no change is position.

Related Questions

An object that moves along a straight line has the velocity-versus-time graph shown in the figure below. At time t = 0, the object has position x = 0.

a. At time t = 5 s, is the acceleration of the object positive, negative, or zero?

b. At time t = 8 s, is the object speeding up, slowing down, or moving with constant speed?

c. Write an expression for the position of the object as a function of time.

d. Use your expression from part (c) to determine (if any) at which the object reaches its maximum position.

ultramarineprairie-dog401

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.