Newton’s 1 and 2 and Egg Drop Review

Materials to Study 6.1 Force and Motion worksheet Solving Fnet Problems: Fa vs. Fg worksheet The Friction Force worksheet Grip, Slip, and Slide worksheet The Elevator Ride (on website now) Skills Sheet 6.2 Conceptual Physics video notes and Discussion Qs Newton’s Laws Tri-fold (brochure) Notes on Newton’s 2nd Law Egg Drop Physics Powerpoint Free Body Diagram Powerpoint Is your toolkit prepared?

Question #1 You are standing in a moving bus, facing forward, and you suddenly fall backward. You can imply from this that the bus’s Velocity increased Velocity decreased Speed remained the same, but it’s turning to the right. Speed remained the same, but it’s turning to the left.

Question #2 The coefficient of friction is a measure of The force with which an object resists movement against a surface. The ratio of the force of friction between two surfaces and the force holding the surfaces together. The ratio of the force of friction between two surfaces and the applied force. The force pushing two surfaces together.

Question #3 When you sit at rest on a chair, the net force on you is zero. up down. Dependent on your weight.

Question #4 A 20 N weight and a 5.0 N weight are dropped simultaneously from the same height. Ignore air resistance. What happens, and why? The 20 N weight accelerates faster because it is heavier. The 20 N weight accelerates faster because it has more inertia. The 5.0 N weight accelerates faster because it has a smaller area. They both accelerate at the same rate because they have the same weight to mass ratio.

Questions #5 The force that keeps you from sliding on an icy sidewalk is Weight. Kinetic friction Static friction. Normal force.

Question #8 A brick and a feather fall to the earth at their respective terminal velocities. Which object experiences the greater force of air resistance? The feather. The brick. Neither, both experience the same amount of drag. It cannot be determined because there is not enough information given.

Question #10 An object sits on a frictionless surface. A 16 N unbalanced force is applied to the object, and it accelerates at 2.0 m/s2. What is the mass of the object? 4.0 kg 8.0 kg 32 kg 78 N

Question #11 Which of the following does not affect air resistance? Cross-sectional area. Drag coefficient Weight. Velocity.

Question #12 A person of weight 480 N stands on a scale in an elevator. What will the scale be reading when the elevator is accelerating upward at 4.00 m/s2? 480 N 676 N 284 N 196 N

Question #13 A horizontal force of 5.0 N accelerates a 4.0 kg mass, from rest, at a rate of 0.50 m/s2. What friction force acts on the mass? 2.0 N 3.0 N 4.0 N 5.0 N

Question #14 Mass and weight Both measure the same thing. Are exactly equal. Are two different quantities. Are both measured in kilograms.

Question #15 A constant net force acts on an object. Describe the motion of the object. Constant acceleration Constant speed Constant velocity Increasing acceleration.

Question #16 Discuss…. Why do you have to push harder on the pedals of a single-speed bicycle to start it moving than to keep it moving at a constant velocity? (make sure to state which law you are using to answer this.) The inertia of the bike demands that you apply a net force to accelerate it from rest. Once it is moving, you no longer have to use much force because “objects in motion tend to stay in motion”. The only force required is that necessary to overcome friction, or accelerate to a higher speed.

Question #17 Discuss… Before a sky diver opens his parachute, he may be falling at a velocity higher than the terminal velocity he will have after the parachute opens. Describe what happens to his velocity as he opens his parachute. His velocity reduces rapidly…he decelerates to a the new terminal velocity. Describe his velocity from after his parachute has been open for a time until he is about to land. After reaching the new terminal velocity, he keeps this velocity until he hits the ground.

Question #18 Solve. A person on a scale rides in an elevator. If the mass of the person is 60.0 kg and the elevator accelerate downward with an acceleration of 4.90 m/s2, what is the reading on the scale? 294 N

Question #19 Discuss. From the top of a tall building, you drop two table tennis balls, one filled with air and the other with water. Both experience air resistance as they fall. How does the air resistance of the two compare for any given velocity? (it is the same, since V, A, and Cd are all the same) Which ball reaches terminal velocity first? (the air filled ball) Do both his the ground at the same time? Explain. (The water filled ball reaches the ground first. The air filled ball reaches terminal velocity and stops accelerating, while the water filled ball continues to accelerate, therefore achieving a higher velocity and covering the distance in less time.)

Question #20 A 250 kg crate is pushed horizontally with a force of 650 N. If the coefficient of friction is 0.25, calculate the acceleration of the crate. 0.15 m/s2