The Science Test

 Motion- change in position of an object; occurs when a force acts on an object  Speed- rate of change in object’s position  speed= distance/time or V= d/t

 Displacement vs. distance - displacement has a direction  Velocity vs. speed – velocity has a direction  Velocity = displacement time  Acceleration - rate at which velocity changes  Acceleration = final velocity – initial velocity time

Time (s)Velocity (m/s) The table describes the motion of a soccer ball rolling across a field. Think about how the ball’s velocity in meters per second, changes during each second of time. How can you describe the ball’s motion? a.Constant velocity b.Negative acceleration c.Positive acceleration d.Negative velocity

 A push or pull  Measured in Newtons  An object at rest and an object moving at a constant velocity is being acted upon by a net force of zero

 4 fundamental forces  Gravitational F = G X m1xm2 r  Electromagnetic - force exerted on a charged particle in an electromagnetic field  Strong nuclear force – holds the nucleus together by the exchange of mesons  Weak nuclear force – allows for radioactive decay, particularly beta

 An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by an unbalanced force  Law of Inertia—why we wear seat belts.

 A moving bowling ball has more inertia than a soccer ball moving at the same velocity and is therefore harder to stop.  It has more momentum  Momentum depends on its mass and its velocity

Which of the following is a measure of an object’s inertia? a. Weightc. volume b. Massd. momentum What does Newton’s first law of motion state? a. When one object exerts a force on a second object, the second object exerts a force in strength, but opposite in direction on the first object b. The force acting on an object is equal to the mass of the object multiplied by velocity c. An object at rest remains at rest unless acted upon by an unbalanced force

 F = ma  For every action there is an  equal and opposite reaction

 On Earth, all objects fall with a constant acceleration of 9.80 m/s 2 in the absence of air resistance.  In other words, a falling object’s velocity increases by 9.8 m/s each second it falls!

 Mass—the amount of matter in an object  Weight—the force on a body due to the gravitational attraction of another body  Weight changes based on location.  Mass NEVER changes.

Two 5 kg balls sit on a table. If one of the balls is replaced with a 10kg ball, what is the effect on the gravitational attraction between the two balls? a. It is about ¼ of what it wasc. it is twice what it was b. It is about ½ of what it wasd. it is four time what it was Calculate the weight of an object with a mass of 40 kg. a. 392 N b. 400 N c. 492 N d. 500 N

 Work = Force x Distance  Measured in Newton-meters or Joules  Power = Work Time  Measured in Watts The pitcher does positive work on the ball by transferring energy into it. The pitcher does negative work on it.

 Lever  Inclined plane  Screw  Wheel and axle  Wedge  pulley

A man is holding a very heavy box steady in his arms. Which of the following describes the work being done on the box? a. It is proportional to the force of gravity acting down b. It is proportional to the weight of the box c. It is proportional to the force exerted by the man holding the box up d. It is equal to zero because the box is not moving

A disturbance that transmits energy through a medium or space

The number of events (waves, vibrations, oscillations) that pass a point in a given amount of time, usually a second  High frequency (short wavelength)  Low frequency (long wave-length)  Frequency is related to pitch, the higher the frequency the higher the pitch

 Wavelength - the distance between peak to peak, shorter wavelengths = higher frequency  Amplitude- the maximum displacement  Amplitude is related to intensity, higher the amplitude the higher the intensity (energy). For sound it means higher volume.  Velocity = frequency x wavelength Amplitude

EM waves do not require a medium

 Require a medium  Sound is an example of a mechanical wave  Sound travels best in denser materials and higher temperatures  Earthquakes  Ocean waves

 Reflection—wave bounces off barrier  Refraction—wave changes direction as it moves from one medium to another  Diffraction—the bending of a wave around a barrier

Which electromagnetic waves have the highest energy? a. Gamma raysc. radio waves b. Infrared wavesd. X-rays What occurs when light hits a clear window? a. Most of the light is scattered b. Most of the light is absorbed c. Most of the light is reflected d. Most of the light is transmitted

To increase the strength of an electromagnet by a. Increase the number of coils b. Increase the number of batteries

Magnetic field is strongest where the lines are closest together If you break the magnet, north and south poles will reform on each piece

The movement of electrons in response to a field --- Electricity! The electromagnetic force is one of the 4 forces of nature and is described by Coulomb’s Law

 Charged particles exert forces on each other  Like repels, opposites attract  The greater the distance between the charges the smaller the force

 Static electricity is the charge that stays on an object – does not move  It can be positive or negative  It can be generated by rubbing two objects together and removing “loose” electrons.

 Induction - charge can be generated by bringing a touching charged object close to another one  Conduction – charge can be generated by a charged object to another object

 Electricity is like water flowing through pipes  Charge flows when there is a difference in potential  Current (I) – flow rate (amperes)  Resistance (R) – drag (ohms)  Voltage (V) – force or pressure (volts)

 V=IR Voltage = Current X Resistance SI units  V = volt = 1 joule/1 coulomb  I = ampere = 1 coulomb/ second  R = ohm = 1 volt/amp

 Series Circuit oneall  Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off. R = R1 + R2 + R3 + R4

 Parallel Circuitseveral only the components on that branch will turn off  Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off. 1/R = 1/R1 + 1/R2 + 1/R3

A grocery store checks the details of a credit card by having the customer move a magnetic strip on the card past a wire coil. Which principle explains this process? a. An electrical current produces mechanical energy b. A permanent magnet produces a changing magnetic field c. A changing magnetic field produces an electrical current d. Mechanical energy produces a changing gravitational field

Lisa has a copper wire, a permanent magnet, and an iron rod. What can she do with these items to produce an electrical current? a. Place the wire near the north pole of the permanent magnet b. Move the permanent magnet rapidly over the wire c. Touch the ends of the wire to the poles of the magnet d. Bring the permanent magnet near the end of the iron rod