CHAPTER 12 FORCES JEOPARDY $100 Objects are Lazy Use the Force Copy Cats Even if the Sky is Falling Down Down… Mixed Bag $200 $300 $400 $500 $400 $300 $200 $100 $500 $400 $300 $200 $100 $500 $400 $300 $200 $100 $500 $400 $300 $200 $100 Final Jeopardy Final Jeopardy

According to Newton’s second law of motion, the acceleration of an object equals the net force acting on the object divided by the object’s mass Objects are lazy - $100

Objects are lazy - $200 An airbag is a safety feature that provides an __________ ________ force that prevents passengers from projecting through the windshield. Unbalanced backwards force Unbalanced backwards force

Objects are lazy - $300 What does Newton’s First Law tell us about the direction of the object’s motion when not acted on by an unbalanced force? Objects will continue to stay at rest/stay in motion when forces are balanced Objects will continue to stay at rest/stay in motion when forces are balanced

Objects are lazy - $400 Which universal force acts only on the protons and neutrons in a nucleus Strong nuclear Strong nuclear

Objects are lazy - $500 What are the four fundamental forces?

Use the force - $100 The SI Unit of force is ……. The Newton The Newton

Use the force - $200 When an unbalanced force acts on an object, the object….. accelerates! accelerates!

Use the force - $300 The net force needed to accelerate a 1,357 kg car forward at 8.0 m/s 2 is… 10,856 N F=1,357 (kg) x 8 (m/s 2 ) 10,856 N F=1,357 (kg) x 8 (m/s 2 )

Use the force - $400 A 2.5 kg box is sliding along a level floor. It is slowing down at a rate of 0.45 m/s 2. What is the force of friction the floor is exerting on the box? N N F=ma  F= 2.5 (kg) x 0.45 (m/s 2 )

Use the force - $500 Rewrite Newton’s second law of motion substituting a, acceleration, with the information from the acceleration equation. Explain why this makes sense! F= m x (Vf-Vi) F= m x (Vf-Vi) Tf-Ti Tf-Ti

Copy cats - $100 If two objects with different masses and traveling with different velocities collide, what “law” allows you to predict the motion of the objects after the collision? Law of conservation of momentum Law of conservation of momentum

Copy cats - $200 Calculate the momentum of a pencil sitting on your desk. Explain how you arrived at your answer. Calculate the momentum of a pencil sitting on your desk. Explain how you arrived at your answer. Zero! P=mv P= m X 0 P=0 kg × m/s 2 Zero! P=mv P= m X 0 P=0 kg × m/s 2

Copy cats - $300 The weak nuclear force is associated with Nuclear decay Nuclear decay

Copy cats - $400 Identify the Action force and Reaction force. Identify the Action force and Reaction force. ACTION FORCE—BALLOON PUSING AIR BACKWARDS REACTION FORCE—AIR PUSHING BALLOON FORWARDS

Copy cats - $500 The acceleration due to gravity on the surface of Mars is about one third the acceleration due to gravity on Earth’s surface. The weight of a dog on the surface of Mars is about 1/3 it’s weight on earth’s surface 1/3 it’s weight on earth’s surface

Even if the sky is falling down down… - $100 HOW DO WE CALCULATE THE WEIGHT OF AN OBJECT? HOW DO WE CALCULATE THE WEIGHT OF AN OBJECT? + 50 FOR THE GRAVITATIONAL CONSTANT + 50 FOR THE GRAVITATIONAL CONSTANT W= MASS X GRAVITY 9.8 M/S 2 W= MASS X GRAVITY 9.8 M/S 2

Even if the sky is falling down down… - $200 You won’t fall out of this roller coaster because of? You won’t fall out of this roller coaster because of? Centripetal force Centripetal force

Even if the sky is falling down down… - $300 What is the weakest force? Gravity Gravity

Even if the sky is falling down down… - $400 What is con served when two objects collide in a closed system? Momentum Momentum

Even if the sky is falling down down… - $500 It usually takes more force to start an object sliding than it does to keep an object sliding because static friction is usually ____________________ than sliding friction. Greater (Larger) Greater (Larger)

Mixed Bag - $100 What kind of friction occurs as a fish swims through water? What kind of friction occurs as a fish swims through water? Fluid friction Fluid friction

Mixed bag- $200 As the polar bear slides across the snow, the sliding friction acting on the bear … Acts in the direction opposite of motion. Acts in the direction opposite of motion.

mixed bag- $300 The forces acting on the falling meatballs are? The forces acting on the falling meatballs are? Gravity and air resistance Gravity and air resistance

Mixed bag - $400 An open parachute increases air resistance of a falling sky diver by Increasing Increasing

Mixed bag - $500 Projectile motion is Projectile motion is caused by the downward force of gravity and an initial forward velocity.

Final Jeopardy an orange might roll off your cafeteria tray when you stop suddenly because of the orange’s inertia