Journal 12/18 revised

1. Jon draws two force diagrams to represent two different objects of interest which are the forces acting upon the ball and the forces that act upon Chris. Yes, two force diagrams are needed because we need to find FnetY, which is the accumulative forces in the Y direction.

2. Yes the calculation will produce the correct mass of Chris because when we find the ball's force which which is in the negative direction, we take the force and subtract it from 2000N and divide by the gravitational constant which should be the correct mass.

3. Two things are wrong/missing. Fearth on Ball in the second diagram should be Fball on Chris . FnetX, we do not know whether or not there are any unbalanced forces in the X direction that may come into effect.

Journal 12/18

1. The two forces are drawn to show the forces on the ball and the forces on Chris. Two different objects of reference. Yes, two force diagrams are needed to determine the answer of the question, which is solving for FnetY.

2.Yes, because when finding the FnetY Force - 2000 divided by the gravitational constant that should be equal to the mass.

3. FnetX is non-existent in the force diagrams, which should be there. In the second force diagram, it should be Force of the Ball on Chris rather than Force of Earth on Ball.

Homework 12/17

Choice C:
By exerting a force that isn't perfectly horizontal or vertical, the object has two more forces that need to be found. The forces added would be Fp on obj. x and Fp on obj. y. These two forces added together should be the original force that was exerted on the object, this can be found by what we learned in lesson 16.

Journal 12/11

1)To represent a cart with the hand acting upon it, the bob in motion, the bob at rest, and the cart in motion
2) The solutions turned out to be the same.
3) The arrow's length changes because of what is stated in Newton's Third Law.
4)We are able to know the force is not zero when it is moving because there is a force of string on the cart.

Homework 12/7

a) When the Earth exerts a force on the book, the book exerts a force on __________
b) When a table exerts a force on the book, the book exerts a force on _________
c) When a tennis racket exerts a force on the ball, the ball exerts a force on_________
d) When car tires push back on the Earth’s surface, the Earth’s surface _________

a) The earth
b) The table
c) The tennis racket
d) exerts a force on the tires.

Journal 12/4

1] A(m) = Fnet
2] In agreement, the acceleration of both objects are the same; the mass does not affect the velocity of the object.
3] In disagreement, the bricks should fall at the same rate and no matter how many bricks there are, the force of the earth on the object is still the same no matter what object.

Homework 12/1

b) You pull a 20-kg sled, exerting an unbalanced, horizontal force of 30 N on it for 10
seconds. (1) What is the acceleration of the sled? (2) What is the speed of the sled after 3
seconds? (3) What force do you need to exert on the sled if you wish to keep it going at
that constant velocity?

Y+
| /\
| - | 30 N +
| 20kgO---->
| |
| \/
|_____________X +

Acceleration = Force
------
Mass

Acceleration= 30N
-----
20kg

Acceleration = 1.5m/s

Speed of sled after 3 seconds is 4.5 m/s assuming pulling the sled started from a 0 velocity

An opposing force at the same rate of acceleration is needed to keep the sled moving at a constant velocity