Physics Chapter 2 Concepts



Q1: How do you REDUCE sliding friction? A1: Make the surfaces smoother, reduce the surface areas of the two objects that are sliding past each other, add a lubricant, or add wheels to the object you are trying to move.
Q2: How do your REDUCE rolling friction? Q2: Reduce Rolling Friction by ---- 1) Making the wheels and the surface smoother; 2) Reduce the surface area of the wheel that touches the road; 3) Reduce the mass of the object above the wheels.
Q3: How do you REDUCE fluid friction? A3: You REDUCE fluid friction by 1) Making the object more aerodynamic (smoother outside so the air or water flows over it more easily); 2) Reduce the surface area exposed to the fluid (as in using a catamaran ... a multi-hull boat ... to spread out the weight of the boat and have less surface area touching the water); 3) Decrease the density of the fluid (this one is hard to do!).
Q4: What is Newton's 1st Law? A4: An object at rest stays at rest and an object in motion stays in motion unless acted upon by an outside force.
Q5: What is Newton's 2nd Law? A5: Force = Mass x Acceleration. In other words, the mass of an object affects its acceleration and force. The more mass an object has, the more force is needed for it to attain the correct acceleration.
Q6: What is Newton's 3rd Law? A6: For every action there is an equal and opposite reaction.
Q7: What are some examples of Newton's 1st Law? A7: Example of Newton's 1st Law would include: a bicycle coasting down a hill, a baseball or soccer ball flying through the air, a paper airplane sailing across a room, a pencil lying on a table, or you sitting in a chair.
Q8: What are some examples of Newton's 2nd Law of Motion? A8: Examples of Newton's 2nd Law of Motion include: 1) Pushing a big box across the floor (large mass requires more force); 2) a baseball hitter using a LOT of force to hit a baseball; 3) a weight lifter lifting barbells; 4) a man pushing a box up an inclined plane.
Q9: What are some examples of Newton's 3rd Law of Motion? A9: Examples of Newton's 3rd Law include... 1) A rocket taking off (propellant goes down, rocket goes up); 2) Pushing off from a wall while standing on a skateboard (push against wall, skateboard goes in opposite direction); 3) Firing a gun (bullet goes out gun nozzle, gun causes "kickback" and knocks hunter backwards; 4) Person on canoe steps off towards dock & canoe goes backwards in opposite direction.
Q10: What is INERTIA? A10: Inertia is that quality that defines an object in motion or at rest. It is connected with Newton's 1st Law of Motion.
Q11: When do you ADD forces? A11: You ADD forces when they are going in the same direction. (For instance: If you are going downstream at 4 km/hr and the stream flows at 4 km/hr your total speed is 8 km/hr downstream.)
Q12: When do you SUBTRACT forces? A12: You SUBTRACT forces when they are opposite in direction. (For instance, if you are going up stream at 2 km/hr and the stream flows at 8 km/hr, your actual speed upstream is 6 km/hr.)
Q13: What is FORMULA for Newton's 2nd Law of Motion? A13: The formula for Newton's 2nd Law of Motion is Force = Mass x Acceleration.
Q14: What is the unit of measurement for Newton's 2nd Law of Motion? A14: The unit of measurement for Newton's 2nd Law of Motion is kg-m/sec/sec or "Newtons."
Q15: How is WEIGHT measured on any planet? A15: WEIGHT is measured on any planet by determining the acceleration due to gravity. The formula used is .... Force = Mass x Acceleration.
Q16: What are the two FACTORS that influence GRAVITY? A16: The two FACTORS that affect Gravity are .... 1) Mass .... and..... 2) Distance. The greater the mass, the greater the gravity. The closer the distance, the greater the gravity. If objects are small in size there is little gravity that you can detect. If objects are far apart, gravity has little effect.
Q17: How is Space Flight influenced by Newton's 1st Law? A17: Newton's 1st Law allows space flight to occur because: 1) Once the rocket clears the gravity of Earth it will COAST all the way to the moon since there is no additional force acting upon it (an object in motion stays in motion); 2) A force is needed to propel the rocket away from the earth's surface (an object at rest will remain at rest): and 3) If the space ship reaches say the moon, it will need thrusters to be able to redirect it's trajectory due to the outside force of the gravity of the moon that it will encounter (an object in motion will stay in motion until it encounters an outside force.)
Q18: How does Newton's 2nd Law of Motion relate to Space Travel? A18: Newton's 2nd Law of Motion influences Space Travel in the following ways: 1) Since the rockets and space shuttle have great mass, Newton's 2nd Law tells scientists that they must create rockets that will have enough FORCE to propel the spacecraft into orbit. The more mass they want to lift, the more force they must apply to break free of earth's gravity.
Q19: How has Newton's 3rd Law of Motion contributed to the development of Space Flight? A19: Without Newton's 3rd Law we wouldn't be able to get off the ground! Propellant that comes out of the bottom of the rocket forces the rocket to move in the opposite direction (For every action there is an equal and opposite reaction.) Once the rocket is in orbit, firing the "thrusters" in the opposite direction makes you move ahead.

This page was created at 3/1/2005