Mohammed+Barajaa

i. Finding the value of A and B:

a) A+B = 6.0i^ + 1.0 j^ A-B = -4.0i^ + 7.0j^

By adding the 2 equations up and canceling the Bs together we end up with: 2A = 2.0i^ + 8j^ Dividing the whole equation by 2, we end up with the value of A as following: A = 1.0i^ + 4j^ To find the value of B we pick one of the previous equations and plug the value of A in as following: A+B = 6.0i^ + 1.0j^ we plug the value of A as: (1.0i^ + 4j^ ) +B = 6.0i^ + 1.0j^ So B will be equal to B = 5.0i^ - 3.^.

ii. Finding the magnitudes of A and B. For A we do: sqrt((1)^2+(4)^2), and we end up with sqrt(17) as an answer. For B we do: Sqrt((5)^2+(3)^2), and we end up with sqrt(34) as an answer.

iii. Finding the angle between A and B:

For the angle of A we do : tan^-1(4/1) = 75.96 Degree For the angle of B we do : tan^-1(3/5) = 30.96 Degree.

**Professor** : Please finish the work by 9 pm Thursday ! First two parts of the problem, you did right, for the last part, please refer to my page. Try to avoid numbers as much and give the steps. This whole process is used to enhance your critical thinking abilities

__** Week(4) **__

For this problem, we will not be using the mass of the rock. .

The given values are as following : 1- Vo = 10.5 m/s. 2- the angle = 54 degree. 3- Vx = 15.3 4- Vy (the height of the building) = ? 5- ay = 9.8 m/s^2 6- ax = 0 m/s^2 We first use the equation (X-Xo) = (Vx)(cos Theta).t - (1/2).ax.t^2, to find the value of t, and since ax = 0 m/s^2, we get (X-Xo) = (Vx)(cos Theta).t. And then we get t. After finding the value of t, we can use the equation (Y-Yo) = (Vy)(sin Theta).t - (1/2).ay.t^2 to find the value of (Y-Yo) which is the height of the building.


 * Professor's Note : Good Job ! visit my page for hints for the Quiz **


 * Week 5 **

1)First, the pelicans initial speed needs to be found. 2) Plug in givens into the equation of y-y0 = Vo*t+.5*a*t^2. 3)Now solve for t. It is now possible to solve for the horizontal component knowing t. 4) Because the this is all done perfectly horizontal Vox = Vo.

5)Use the new speed. 6) Plug back in for new height and solve for t. 7) With new time and old velocity, solve for the horizontal displacement or X-Xo.

__**Week7:**__ 01 . An object is hung from a spring balance attached to the celing of an elevator cab. The balance reads 65 N, when the cab is standing still. What is the reading when the cab is moving upward, (a) with a constant speed of 8 m/s and (b) with a speed 8 m/s while decelerating at a rate of 2.4 m/s²

In this problem, F = T, because the spring balance measures the tensionT. a) T= ma + mg, a = 0 m/s^2,  T= mg  T= 65N.

b) T = mg + ma a = -2.4 (the negative sign was put because it's deceleration)  T = mg + m(-2.4)  T= 49N.

Professor's Note : Good job, avoid careless mistakes, I fixed one

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__** Week 08 (March, 12th, 2012) **__

01. A loaded sled weighing 85 N rests on a plane inclined at an angle of 20⁰ with the horizontal. The coefficents of static and kinetic friction between the inclined plane and the sled are 0.25 and 0.15 respectively.

a). What is the least magnitude of the force F, parallel to the plane, that will prevent the sled from slipping down the plane

b). What is the minimum force required to start the sled moving upward?

c). What value of F (force) is required to move the sled up the plane at constant velocity?



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1) A cord is used to vertically lower an initially stationary block of mass M at a constant downward acceleration of g/4. When the block has fallen a distance d i) Find the work done by the cord's force on the block ii) Find the work done by the gravitational force on the block iii) Find the kinetic energy of the block iv) Find the speed of the block