NLN PAX Science: Physics Questions and Answers Already Passed

NLN PAX Science: Physics Questions and Answers Already Passed 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