Presentation on theme: "Physical Science Final Exam Review Miss Glover. Motion Distance in meters: How far you have traveled Velocity in m/s: How fast you are going Acceleration."— Presentation transcript:
Motion Distance in meters: How far you have traveled Velocity in m/s: How fast you are going Acceleration in m/s 2 : Rate of change of velocity- speeding up, slowing down or turning! Equations: Constant VAcceleration Graphs: d d t t
Example: A truck drives 1000 km in 10 hours, what is it’s speed? d=1000km t=10 hours v=? v=d/t=1000/10= 100km/hr A boat travels for 5 hours at 20 miles per hour, How far does it go? t=5 hr v=20mi/hr d=? d=v(t)=20(5)= 100 mi
Acceleration A PR runner accelerates from rest to 10 m/s in 4 seconds, what is her acceleration? Vi=0m/s Vf=10 m/s, t=4 sec a=? A=(Vf-Vi)/t= (10-0)/4= 2.5 m/s/s
Freefall ALL objects accelerate towards the Earth at g=10 m/s 2 due to the large mass of the Earth An object that is accelerating is increasing velocity at 10 m/s each second downwards, or decreasing the velocity by 10 m/s each second as it goes upwards. The distance an object goes while accelerating increases proportional to the time squared. EQ:
Projectiles Combine a constant velocity problem horizontally, and a free fall acceleration problem vertically (g=10!). A ball dropped will hit the ground at the same time as a ball given an initial velocity horizontally. The only force acting on a projectile is gravity! Horizontal Angle
Forces- Newton’s Laws 1 st Law: Inertia: An object in motion stays in motion, and an object at rest stays at rest, UNLESS acted upon by an outside net force. 2 nd Law: F=ma: A net force causes a mass to accelerate. 3 rd Law: Action/Reaction: For every force there is an equal and opposite reaction force. EQ:
Forces Units of force are Newtons= kg (m/s 2 ) Defined as a push or a pull Some forces we have considered: Force of Gravity (Weight) Fg=m(g)= m(10) m= mass in kg Force of Friction: A force OPPOSING the motion of two surfaces over each other. Always in the direction opposite the motion. Can be helpful- like providing traction to a car or Can be a hindrance-may cause your brakes to heat up
Energy Units of Joules Potential Energy is energy stored up due to an objects location in the gravitational field (a height off the ground!) Kinetic Energy is energy due to an object’s motion. If energy is conserved, the energy at the PE at the top of a tree or coaster will equal the KE at the bottom.
Work and Power You give objects energy (PE or KE) by doing WORK! To do work you apply a force over a distance. Work will equal the energy you gain, so it also has units of Joules. Power is the rate of doing work or the Work/Time
Work Example A force of 20 N is applied to a box to move it a distance of 8 m, how much work is done? F=20 N, d=8m, W=? W=F(d)= 20(8)= 160 J
Simple Machines Used to reduce or change the direction of a force needed to do work by increasing the distance over which the force is applied. Seven Types: Lever, Pulley, Inclined Plane, Gear, Wheel and Axle, Wedge, Screw Simple machines involved just one motion- ramp, door knob, handle etc… two or more simple machines may be combined to make a complex machine like a wheel barrel or a bike!
Simple Machine Calculations The ratio of the force you get from a machine compared to the force you need to apply is called the Mechanical Advantage (MA). The ratio of the distance you must apply the force compared to the distance the machine applies the force is called the Ideal Mechanical Advantage (IMA)
Simple Machines Examples A lever is used to lift a 10,000 lb car with a force of 500 lbs, what is the mechanical advantage of the lever? Fe=500 lbs, Fr=10,000 lb MA=Fr/Fe MA= 10000/500 =20 (no units!) A inclined plane is 10 feet long and 2 feet tall, what is the Ideal Mechanical Advantage? de=10ft, dr=2 ft, IMA=de/dr IMA=10/2=5 (mo units!)
Momentum A object that is moving has momentum! Momentum (p)= mass (velocity) units: kg(m/s) The more mass or velocity an object has, the more momentum it has. For a given mass, the faster moving object will have more momentum. Force a given velocity, the more massive object will have more momentum.
Momentum Examples Which has more momentum, a 2000 kg car moving at 1 m/s, or a 1 kg mass moving at 2000 m/s? p=m(v) so they have the SAME momentum! Joe with a mass of 75 kg, runs at 2 m/s during warm-ups and 10 m/s during the race, when does he have more momentum? p= m(v) so more velocity, more momentum!
Momentum and Impulse To change an object’s momentum you could change its mass or velocity. This can be done by altering the object or applying a force! Applying a force over a time is called an Impulse and it will equal the change in momentum. Egg drop/Air bags: Extend the time, reduce the force Follow through: Extend the time to increase the change in momentum.
Waves All waves transport energy through the medium. The medium is the material that the wave is passed on through- water, air, glass… The wave speed will depend on what medium your are traveling through and equals frequency times wavelength
Types of Waves Transverse Waves- Particles move perpendicular to the wave motion. EX: Coil, slinky, guitar string Longitudinal Waves- Particles move parallel to the wave motion. EX: Sound, Grab and release slinky coils. Transverse and longitudinal NEED a medium! Electromagnetic Waves- DO NOT need a medium to be passed on- can travel in a vacuum (empty space)
Parts of a Wave Crests: Top of wave Troughs: Bottom of Waves Wavelength: Distance for one full wave- Crest to Crest (A-E) or (E-H)( ) Compression: High Pressure Region Rarefaction: Low Pressure Region
Wave Behaviors Reflection- bouncing of a wave off of a barrier Refraction-Change in wave speed due to a change in medium Diffraction- Bending of a wave around a barrier Interference- Two or more waves going through he same medium at the same time.
Sound Sound travels fastest in a solid, slowest in cold air The speed of sound depends on the temperature of the air The highness or lowness is the PITCH of a sound The volume of sound is determine by its intensity
Electromagnetic Waves All electromagnetic waves travel at c=3 X 10 8 m/s Exhibit all wave behaviours High frequency Low frequency
Lenses and Mirrors Lenses Refract Light, Mirrors Reflect Light Real- Light rays actually cross (can focus on screen) Virtual- Light rays only appear to cross (cannot focus on a screen) Erect- Right side up Inverted- Upside down Larger/Smaller- Image size compared to object
Lenses and Mirrors Converging: Convex Lens/Concave Mirror ▫Inside the focal point: Larger, Erect, Virtual ▫Outside the focal point: Inverted, Real ▫Examples: Magnifying glass, telescope, make up mirror, glasses Diverging: Concave Lens/Convex Mirror ▫ALWAYS Smaller, erect, virtual ▫Examples: Security mirror, glasses
Ray Diagrams In parallel, out through the focus In through the focus, out parallel Draw an image where the rays meet, or appear to meet. Describe the image as Real or Virtual Erect or Inverted Larger or Smaller