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Transcript
Forces Chapter 10 What is an example of exerting force? Pushing/pulling anything What happens when two forces act in the same direction? They add together The force of gravity on a person or object on the surface of a planet is called Friction Which of the following is an example of rolling friction? Anything rolling When the only force acting on a falling object is gravity, then the object is said to be In free fall Air resistance is a type of Friction The law of universal gravitation states that any two objects in the universe, without exception Attract each other In physical science, a push or a pull is called a Force The amount of matter in an object is called its Mass Which of the following is an example of increasing friction intentionally Throwing sand on an icy driveway The force that pulls falling objects toward Earth is called Gravity Objects falling through air experience a type of friction called Air resistance The SI unit for force is the Newton Balanced forces acting on an object Never change the object’s motion The tendency of an object to resist change in its motion is known as Inertia How can you increase the momentum of an object? By increasing mass or velocity According to the law of conservation of momentum, when two objects collide in the absence of friction, Momentum is transferred and not lost The total momentum of a group of objects is conserved unless Outside forces act on the objects According to Newton’s third law of motion, when a hammer strikes and exerts force on a nail, the nail Exerts an equal force on the hammer What happens when a unbalanced force acts on an object? The objects in motion will accelerate Which of these objects would exhibit the greatest resistance to a change in it’s motion? Heaviest mass Newton’s second law of motion states the relationship of mass, acceleration, and force. It says that F = Mass x Acceleration As the force applied to the object is increases, the objects will also increase. Acceleration A 300 N force acts on a 20 kg object. The acceleration of the object is 15 meters per second squared Compared to a sports car moving at 30 mph, the same sports car moving at 60 mph has Twice as much momentum One way to increase acceleration is by Decreasing mass, Increasing force The product of an object’s mass and velocity is called its Momentum A person standing on roller skates is holding a heavy rock. If he throws the rock horizontally to the right, what will be his resulting motion? To the left The amount of gravity between two objects depends on their masses and Distance between them Forces can be added together only if they are Acting in the same direction A student pushes a lawnmower with a force of 15 N. What is the force exerted by the mower on his hands? 15 N The momentum of an object is in the same direction as its Velocity What happens when two forces act in the same direction? Added together That force that one surface exerts on another when the two rub against each other is called Friction Mass times acceleration equals the net force acting on an object according to which of Newton’s laws? 2nd Law Which has more momentum, a semi-truck moving at 30 mph or a Chevy S10 truck moving at 30 mph? Semi-truck The greater the mass of an object, The greater the inertia Balanced forces acting on an object Never change object’s motion