Prince Sattam University
Department of Electrical Engineering
Communications Principles
Ch1: Background and Preview
Instructor
Dr. Moustafa M. Nasralla
Email: [email protected]
Website: https:/faculty.psau.edu.sa/m.nasralla
The Communication Process
Prince Sattam University
Philadelphia
University
Department of Electrical
Engineering
Department of Communication & Electronics
Engineering
Communications Principles
Analogg Communications
Ch2: Introduction
Instructor
Ib Dr.
Ibrahim
hi Moustafa
N.
N Ab
Ab
A 1100 kg car is traveling at 15 m/s 24 E of N when it
collides with a 1450 kg truck traveling at an unknown angle W
of N. After the collision both vehicles stick together and travel
due North at 9.0 m/s.
What was the magnitude and direction of the truck'
A 4.0 kg object initially at rest explodes into 3 unequal
fragments. A 1.2 kg chunk flies off at 15 m/s 30 N of W and a
0.9 kg chunk moves at 18 m/s 10 E of N.
Find the magnitude and direction of the velocity of the final
piece.
Equilibrium Notes
3 Torque Not at 90o
Although weve already learned about torque, we dont quite have the whole story. So far we have only seen
torque provided by forces acting perpendicular to the body in equilibrium. What happens if a force acts in a
dir
Equilibrium Notes
2 Torque at 90o
A body in translational equilibrium will have no acceleration in the x or y directions. However it still could be
_.
Consider a teeter-totter, with a 100 kg student on one end and a 50 kg student on the other.
What are th
A 1150 kg car starts at rest and accelerates to 55 km/h up
a hill as shown. An average friction force of 250 N acts on
the car the entire time. Calculate the total work done by
the car.
A 1200 kg car starts at 4.0 m/s and accelerates up a 12 m high hill to
a final speed of 18 m/s in 6.0 s. During the process 75000 J of heat
are generated. Find:
a) The power input of the car.
b) The efficiency of the process.
A 1375 kg car traveling 18 m/s West turns a corner and
travels North at 15 m/s. The turn takes a total of 3.6 s.
a. Find the magnitude and direction of the car's impulse.
b. Determine the average net force acting on the car during
the turn.
Work, Energy and Momentum Notes
1 Work and Energy
Work is defined as the transfer of energy
from one body to another.
Or more rigorously:
We can calculate the work done on an object with:
the units of work are Nm or Joules
Note that the
Back in grade 11 it really was that easy
When non-conservative forces (such as friction) act on an object, not all energy is transferred between kinetic and
potential. This is what physicists have termed REALITY. Deal with it.
The work done by fric
Work, Energy and Momentum Notes
3 Momentum and Collisions
Momentum is a quantity of motion that depends on both the
mass and velocity of the object in question.
The units of momentum are:
Remember:
Momentum is a _ quantity, with the
same sign as its veloc
A 2.0 kg bowling ball is traveling east at 5.5 m/s when it
collides with a stationary 0.5 kg bowling pin. After the collision
the bowling pin is traveling due East at 8.8 m/s.
a. Find the final speed of the bowling ball.
b. Prove whether this collision wa
A 68 kg snowboarder is moving down the incline shown at 7.2 m/s.
While sliding down the incline he generates 680 J of heat. At the base
of the incline he hits a jump and becomes airborne. At the top of his
arc he is traveling at 4.4 m/s. What is his maxim
Work, Energy and Momentum Notes
2 Power and Efficiency
In everyday language we often use the words WORK, ENERGY and POWER synonymously. However this makes the
physics gods extremely furious because we should all know that:
POWER is
Mathematically w
A 15.0 kg block is pushed up a ramp as shown by a student
who exerts 135 N over 4.0 s.
a. Determine the power input by the student.
b. What is the efficiency of this process?
A 3.0 m long, 12 kg ladder leans against a frictionless wall as
shown. A 55 kg painter climbs 2.2 m up the ladder. What is the
minimum coefficient of friction between the ladder and the
ground such that the ladder doesn't slip?
Work, Energy and Momentum Notes
3 Momentum and Collisions
Momentum is a quantity of motion that depends on both the mass
and velocity of the object in question.
The units of momentum are:
Remember:
Momentum is a _ quantity, with the
same
A 182 cm tall person lies on a board of negligible mass which
is supported by two scales, one directly under their head and
their feet. The scales read 37.2 kg and 32.8 kg respectively.
How far is the person's center of mass from their feet?
Equilibrium Notes
1 Translational Equilibrium
Ex.
A 20.0 kg object is suspended by a rope as shown.
What is the net force acting on it?
Ex.
Ok that was easy, now that same 20.0 kg object is
lifted at a velocity of 4.9 m/s. What is the net force
acting on
A 62 kg trapeze artist hangs from a bar as
shown. The uniform bar is 1.2 m long and
has a mass of 8.0 kg.
Determine the tension in both chains
supporting the bar.
Work, Energy and Momentum Notes
4 Collisions in 2-D
When dealing with collisions in 2-dimensions it is important to remember that momentum is a vector with magnitude
and direction. When finding the total momentum we have to do:
o
Collisions at 9
A 7.0 kg pumpkin is traveling east at 12 m/s when it
explodes into two unequal fragments. The larger 5.0 kg
fragment travels at 15 m/s at an angle 65o S of E. What is
the speed and direction of the other fragment?
How much force must the
tricep muscle in the upper arm
exert on the lower arm to hold
a 8.2 kg shot put?
Assume the lower arm has a
mass of 2.6 kg and its center
of mass is 13 cm from the
elbow joint.
How much force is exerted by the bicep
muscle shown when holding on to a 3.0
kg ball?
Assume that the mass of the forearm is
2.2 kg and that its center of mass is
located 15 cm from the elbow.