NLN PAX Science: Physics(Answered) Complete Solution

NLN PAX Science: Physics(Answered) Complete Solution aim of physics to understand the physical laws and principles that influence every aspect of daily life displacement of an object the distance that an object is from some starting point, and is measured in units of length How does displacement change when an object is in motion? it is constantly changing How is motion described? by displacement, velocity (speed) and acceleration speed distance traveled by an object per unit of time speed = (distance traveled/time) velocity speed in a given direction What two things does velocity tell us about a moving object? its speed and direction acceleration the rate of change in velocity; can be any change in velocity, either positive or negative. deceleration negative acceleration or a decrease in velocity and can change in direction How is acceleration calculated? (final velocity-original velocity)/time Why can velocity and acceleration be described using vectors? because they have both magnitude and direction What quality do all moving objects have? momentum; an object traveling at a specific velocity has momentum calculate momentum Momentum = mass x velocity conservation of momentum the total movement of an isolated system is always constant, ie during a collision, the momentum of each body changes but the total momentum is conserved. One object may lose momentum, but this momentum is gained by other object How is momentum conserved when a moving object hits a stable object, such as a bullet hitting a wall? the moving object, like the bullet, delivers an impulse to the wall, and this impulse is said to be the change in the objects momentum Newton's first law objects in motion tend to stay in motion and objects at rest tend to stay at rest inertia the property of matter that resists any change in motion Newton's second law describes the relationship between force, mass and acceleration; the force of an object equals the mass of the object times its acceleration f = ma newton the unit that represents a force that accelerates a mass of 1 kg 1 meter per second friction force that is exerted on an object along a surface or whenever an object has a velocity along a surface and the two surfaces touch gravity the force of attraction between all objects in the universe what determines the weight of an object? the pull of gravity on an object Why is the Earth's gravitational force great? because the Earth has a large mass Is the force due to gravity and the acceleration of an object towards earth the same? the force due to gravity is not the same on every object and depends upon the object's mass, and the acceleration toward earth is the same for all objects, independent of their mass How does a change in the force of gravity change an objects weight and mass? it changes the object's weight but not its mass density d=m/v What is torque and what does it measure? the perpendicular force times the lever arm; the ability of a force that is applied perpendicularly to rotate an object around an axis, ie using a wrench to turn a bolt What is centripetal force? continual force on an object pulling it towards the center of the circle What does Newton's third law state? that for every action there is an equal and opposite reaction What is energy? the ability to do work? What are the two types of energy? 1. Kinetic energy 2. Potential energy Describe kinetic energy? energy associated with motion, any moving body has this energy because it is able to do work by moving other bodies; tells us how much work body can do by moving other bodies until it is brought to rest How do you calculate kinetic energy? kinetic energy = 0.5( mass x velocity)^2 What is potential energy? the energy stored in a body because of its position, has more potential energy at the top of a hill than at the bottom What is work? the product of the force applied to an object and the distance through which the force is applied How do you calculate work? work = force x distance What is a joule? the unit of energy equal to the work done by a force of 1 newton acting over a distance of 1 meter What is power? the rate at which work is done What is the formula for power? power = (force x distance)/ time = work/time What is a machine? a device that makes work easier by changing the force or the direction of an applied force What is the efficiency of a machine? the work done divided by the energy used to power the machine Why can't a machine ever be 100% efficient? because of friction What are the six simple machines? 1. inclined plane-slanted surface used to raise an object 2. wedge-moving inclined plane 3. screw-inclined plane wrapped around a cylinder 4. lever-simple machine that is free to move around a fulcrum when force is applied 5. pulley-chain or rope wrapped around a wheel 6. wheel and axle-level that rotates in circle What is a compound machine? two or more simple machines What is an atom? smallest particles of an element that retain all chemical properties of an element What is the kinetic theory of matter atoms in matter are in a constant state of motion What are the three ordinary states of matter, and in which states are molecules free to move around? 1. gas 2. liquid 3. solid free to move around in liquid and gas states Where does pressure come from? it results from the impulses from the collision of molecules with the walls of the container What does Boyle's Law state? the volume of a fixed amount of gas varies inversely with the pressure of the gas. If volume of gas is decreased both the number of particle collisions and the pressure of the gas increase. If volume increases, pressure decreases What does Charles' law state? defines the relationship between the temperature and volume of of a gas. Volume of a fixed amount of gas varies directly with its temperature. If the temperature increases, the volume increases What is temperature? a measure of the average kinetic energy of the particles in a substance; tells how warm or cold a substance is with regards to other substances What does temperature determine? whether a substance gains or gives up heat when put into contact with other bodies. What is heat? a form of energy that causes the particles of matter to move faster and farther apart What is the specific heat of a substance? the heat needed to raise the temperature of 1 gram by 1 degree. What is is a phase change? the physical change of a substance from state to another What is latent heat? the heat energy needed per unit mass to change the phase of a substance What is the ice point? the temperature at which ice melts or water freezes F 32 C 0 What is the steam point? the point at which water at standard pressure boils C 100 F 212 What is the triple point? point on the Kelvin scale where water exists simultaneously as a gass, a liquid and a solid. What is absolute zero? the lowest possible temperature on the Kelvin scale. What is motion? a change in position relative to a frame of reference What is a wave? a rhythmic disturbance that travels through matter or space What does wave motion accomplish? a means of transferring energy What are the two types of waves? transverse waves and longitudinal What is a transverse wave? a wave in which matter vibrates at right angles to the direction in which the wave travels, ie waves on the ocean What is a longitudinal wave? a wave in which matter vibrates back and forth along the path that the waves, ie sound waves What is periodic motion? motion that repeats itself over and over again, such as the motion of a pendulum What is a periodic wave? a motion that repeats itself at regular intervals and that transfers energy but not mass What is a period? the time it takes for motion in a periodic wave to repeat itself and is measured in seconds