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Objective 5. MOTION & FORCES. Have this on your desk for EVERY question involving math. EVERY FORMULA YOU NEED IS ON THE CHART. You won’t ALWAYS use all the numbers given. Eliminate bad answers. ALWAYS use your calculator!!!!. FORMULAS. Constants & Conversions. Ruler. - PowerPoint PPT Presentation
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Objective 5
MOTION & FORCES
Have this on your desk for EVERY question involving math.
FORMULAS
Constants & Conversions
Ruler
EVERY FORMULA YOU NEED IS ON THE CHART.You won’t ALWAYS use all the numbers given.Eliminate bad answers.ALWAYS use your calculator!!!!
• Average velocity (speed) is the change of position of an object over time. Velocity is a vector quantity that includes direction.
SPEED describes how fast an object moves.
Speed (v) = Distance Time
AccelerationChange in velocity over
change in time
a =final velocity – initial velocity
∆T
Acceleration
0
20
40
60
1 3 5 7 9 11 13 15
Time (sec)Ve
loci
ty ((
m/s
)(m)
(slope)
Units for acceleration m/s/s or m/s2
• A 2.4 km
• B 2.4 m
• C 23 cm
• D 24 mm
The speed of sound in human
tissue is about 1600 m/s. If an
ultrasound pulse takes 1.5 x 10-5s
to travel through a tissue, what is
the thickness of the tissue?
TIME
DISTANCESpeed = distance
time
1600m/s = distance
1.5 x 10-5 s
.024m = distance
The table above shows experimental data collected when four cars moved along a straight-line path. According to these data, which car moved with a constant acceleration of 2 m/s2 ?
A Car QB Car RC Car SD Car T
a =final velocity – initial velocity ∆T
You can immediately eliminate Q & R…WHY?
A(carS) = 4m/s-2m/s = 2m/s
2s-1s 1s
Use this method to check car S & car T.
Newton’s 1st Law of Motion
A body in motion will remain in motion.
A body at rest will remain at rest.
UNLESS there is a force acting on that object.
Newton’s 2nd Law of Motion
Force = mass x acceleration
Newton’s 3rd Law of Motion
For every action (force) there is an equal and opposite reaction (force).
Friction
A force that acts in a direction opposite to the motion of two surfaces in contact with each other.
MOMENTUM
• The effect of motion is momentum.
• Momentum = Mass x Velocity
Work• Work: amount of energy
transferred by a force
• W = F x d
• The work done by forces on an object = changes in energy for that object.
• Work and Energy are measured in Joules
• 1 Joule=1 Newton • meter
Machines use power
• Power: the rate at which energy is used (work is done)
• P=Work/time• Power is measured in
H.P. or watts• 1 watt = 1 Joule
1 sec
SIMPLE MACHINESmake WORK easier
3 Classes of LEVERS
(Resistance)
The human bicep muscle is a classic example of a third class lever. Similar analogies can be drawn from almost all joints in the human body.
•
% Efficiency• NO MACHINE IS 100%
efficient.
• Energy is lost as HEAT!!!
%efficiency = work output X 100 work input
WAVES
Velocity of a wave = frequency x wavelength(m/s) (Hz) (m)
ν = ƒ x
KINETIC ENERGY- energy of motion
KE= ½ (mass x velocity)2
GRAVITATIONAL POTENTIAL ENERGY
PE= mass x acceleration due x heightto gravity
ENERGY = mass x (speed of light)2
Current = Voltage / Resistance
Electrical Power = Voltage x Current
Electrical energy = power x time
Electricity – flow of electrical charge
Convection, Conduction, and Radiation
• Convection- Heat transfer by the mass movement of molecules
•
Convection, Conduction, and Radiation
• Conduction- Heat transfer by the collision of molecules that are in contact
Convection, Conduction, and Radiation
• Radiation- Heat transfer with no physical contact
Convection, Conduction, and Radiation
.
PRACTICE WITH YOUR FORMULA CHART
• EVERY FORMULA YOU NEED IS ON THE CHART.
• You won’t ALWAYS use all the numbers given.
• Eliminate bad answers.
• ALWAYS use your calculator!!!!
Density of an object is 1.25 g/ml at 20°C and the mass is 4 g, what is the
volume?
An object falling from the sky traveled
4000 m in 8 seconds, what is the
speed of the object?
A car accelerates from 0 m/s to 100 m/s in 5 seconds.
What is the acceleration of the
car?
A 0.75 kg ball is thrown with a velocity of 40 m/s,
what is the momentum of the ball?
A 25 kg rock is increasing in velocity from 0 m/s to 50 m/s
in 10 seconds. What is the rock’s force?
If a box is moved 5 m with a force of 100 N, how much work
is done?
How much power is the result of
completing 5000 J of work in 30 seconds?
What is the % efficiency of a
machine if the work output is 40 J and
the work input is 50 J?
What is the kinetic energy of a 100 kg object traveling a 5
m/s?
What is the potential energy of a 50 kg rock sitting on
top of a 75 m cliff?
What is the velocity of a wave with a
frequency of 1000 hz and a
wavelength of 0.00000045 m?