Newton’s Laws 4B investigate and describe [applications of] Newton’s laws such as in vehicle restraints, sports activities, geological processes, and satellite orbits;

Law of Inertia First Law An object in motion remains in motion or an object at rest remains at rest unless acted on by an unbalanced force. With seat belt. Without seat belt.

FIRST LAW FORCES Forces are on one object; forces are balanced. Force to the right = 500N Force to the left = 500N Net Force = 0N

FIRST LAW MOTION: Object will be at rest or moving at a constant velocity.

Practice Question 1 A wet bar of soap slides 1 meter across a wet tile floor without appearing to slow down. Which of these statements explains why the bar of soap fails to slow down? a. A constant force on an object produces constant positive acceleration. b. A moving object having constant velocity contains kinetic energy. c. An object in motion tends to remain in motion in the absence of an external force. d. An object’s weight is proportional to its mass.

Practice Question 1 A wet bar of soap slides 1 meter across a wet tile floor without appearing to slow down. Which of these statements explains why the bar of soap fails to slow down? a. A constant force on an object produces constant positive acceleration. b. A moving object having constant velocity contains kinetic energy. c. An object in motion tends to remain in motion in the absence of an external force. d. An object’s weight is proportional to its mass.

Newton’s Second Law Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). EQUATION: FORCE = mass X acceleration = kg X m/s2 = newtons

SECOND LAW FORCES: Forces are on one object; forces are unbalanced. Force to right = 200N Force to left: = 50N Net Force = 150 N to right

SECOND LAW MOTION: Object will accelerate – change speed or direction.

Free - Fall Motion under the force of gravitation only Acceleration due to gravity = 9.8 m/s 2

Practice Question 2 2.The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s 2, what is the force the frog exerts on the lake’s bank when leaping? a. 0.2 N c. 1.5 N b. 0.8 N d. 6.0 N

Practice Question 2 2.The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s 2, what is the force the frog exerts on the lake’s bank when leaping? a. 0.2 N c. 1.5 N b. 0.8 N d. 6.0 N F = m x a = 0.5 kg x 3 m/s2 = 1.5 N

Practice Question 3 3. What is the net force exerted on a 90.0 kg race-car driver while the race car is accelerating from 0 to 44.7 m/s in 4.50 9.8 N 20 N 201 N 894N

Practice Question 3 3. What is the net force exerted on a 90.0 kg race-car driver while the race car is accelerating from 0 to 44.7 m/s in 4.50 9.8 N 20 N 201 N 894N

Third Law For every action force there is an equal and opposite reaction force. Action Force: Rocket pushes gases down. Reaction Force: Gases push rocket up.

Practice Question 4 4. After shooting a cannonball, a cannon recoils with a much lower velocity than the cannonball. This is primarily because, compared to the cannonball, the cannon has a — a. much greater mass b. greater kinetic energy c. smaller amount of momentum d. smaller force applied to it

Practice Question 4 4. After shooting a cannonball, a cannon recoils with a much lower velocity than the cannonball. This is primarily because, compared to the cannonball, the cannon has a — a. much greater mass b. greater kinetic energy c. smaller amount of momentum d. smaller force applied to it

THIRD LAW FORCES: Forces are on two different objects; Forces are equal but in opposite directions Action Force: Baseball pushes glove leftward. Reaction Force: ___________________ Glove pushes baseball rightward.

THIRD LAW Action Force: _____________________ Ball pushes bat leftward. Reaction Force: Bat pushes ball rightward.

Question Practice

1. The picture above shows the directions in which water leaves this scallop’s shell. Which picture below shows the direction the scallop will move?

1. The picture above shows the directions in which water leaves this scallop’s shell. Which picture below shows the direction the scallop will move? D

2. A wet bar of soap slides 1 meter across a wet tile floor without appearing to slow down. Which of these statements explains why the bar of soap fails to slow down? A constant force on an object produces constant positive acceleration. An object in motion tends to remain in motion in the absence of an external force. A moving object having constant velocity contains kinetic energy. An object’s weight is proportional to its mass.

2. A wet bar of soap slides 1 meter across a wet tile floor without appearing to slow down. Which of these statements explains why the bar of soap fails to slow down? A constant force on an object produces constant positive acceleration. An object in motion tends to remain in motion in the absence of an external force. A moving object having constant velocity contains kinetic energy. An object’s weight is proportional to its mass.

The puck’s temperature changed. An upward force acted on the puck. 3. A hockey player pushed a puck toward the opposite side of a level ice rink. The player expected the puck to continue all the way across the ice, but the puck slowed and stopped before reaching the other side. Which of these best explains why the puck failed to slide all the way to the opposite side? The puck’s temperature changed. An upward force acted on the puck. The puck’s momentum remained unchanged. An opposing force acted on the puck.

The puck’s temperature changed. An upward force acted on the puck. 3. A hockey player pushed a puck toward the opposite side of a level ice rink. The player expected the puck to continue all the way across the ice, but the puck slowed and stopped before reaching the other side. Which of these best explains why the puck failed to slide all the way to the opposite side? The puck’s temperature changed. An upward force acted on the puck. The puck’s momentum remained unchanged. An opposing force acted on the puck.

4. The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s2, what is the force the frog exerts on the lake’s bank when leaping? 0.2 N 0.8 N 1.5 N 6.0 N

4. The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s2, what is the force the frog exerts on the lake’s bank when leaping? 0.2 N 0.8 N 1.5 N 6.0 N

5. Which of these is the best description of the action-reaction force pair when the space shuttle lifts off from the launch pad? The ground pushes the rocket up while exhaust gases push down on the ground. Exhaust gases push down on air while the air pushes up on the rocket. The rocket pushes exhaust gases down while the exhaust gases push the rocket up. Gravity pulls the rocket exhaust down while friction pushes up against the atmosphere.

5. Which of these is the best description of the action-reaction force pair when the space shuttle lifts off from the launch pad? The ground pushes the rocket up while exhaust gases push down on the ground. Exhaust gases push down on air while the air pushes up on the rocket. The rocket pushes exhaust gases down while the exhaust gases push the rocket up. Gravity pulls the rocket exhaust down while friction pushes up against the atmosphere.

smaller amount of momentum greater kinetic energy 6. After shooting a cannonball, a cannon recoils with a much lower velocity than the cannonball. This is primarily because, compared to the cannonball, the cannon has a — much greater mass smaller amount of momentum greater kinetic energy smaller force applied to it

smaller amount of momentum greater kinetic energy 6. After shooting a cannonball, a cannon recoils with a much lower velocity than the cannonball. This is primarily because, compared to the cannonball, the cannon has a — much greater mass smaller amount of momentum greater kinetic energy smaller force applied to it

7. Which factor would most likely cause a communications satellite orbiting Earth to return to Earth from its orbit? An increase in the satellite’s forward momentum An increase in solar energy striking the satellite A decrease in the satellite’s size A decrease in the satellite’s velocity

7. Which factor would most likely cause a communications satellite orbiting Earth to return to Earth from its orbit? An increase in the satellite’s forward momentum An increase in solar energy striking the satellite A decrease in the satellite’s size A decrease in the satellite’s velocity

What goes up must come down. 8. When the air is released from a balloon, the air moves in one direction, and the balloon moves in another direction. Which statement does this situation best illustrate? What goes up must come down. For every action there is an equal and opposite reaction. The shape and size of an object affect air resistance. The acceleration due to Earth’s gravity is 9.8 m/s2.

What goes up must come down. 8. When the air is released from a balloon, the air moves in one direction, and the balloon moves in another direction. Which statement does this situation best illustrate? What goes up must come down. For every action there is an equal and opposite reaction. The shape and size of an object affect air resistance. The acceleration due to Earth’s gravity is 9.8 m/s2.

9. Which of these would cause the gravitational force between Earth and the sun to decrease? An increase in the length of a day on Earth An increase in the distance between Earth and the sun An increase in the number of planets orbiting the sun An increase in the masses of Earth and the sun

9. Which of these would cause the gravitational force between Earth and the sun to decrease? An increase in the length of a day on Earth An increase in the distance between Earth and the sun An increase in the number of planets orbiting the sun An increase in the masses of Earth and the sun

10. An athlete sitting in a wheelchair at rest throws a basketball forward. Since the athlete and the wheelchair have greater mass than the basketball has, the athlete and the wheelchair will — move backward at a lower speed than the basketball moves forward travel the same distance as the basketball but in the opposite direction move backward at a higher speed than the basketball moves forward have the same forward momentum as the basketball

10. An athlete sitting in a wheelchair at rest throws a basketball forward. Since the athlete and the wheelchair have greater mass than the basketball has, the athlete and the wheelchair will — move backward at a lower speed than the basketball moves forward travel the same distance as the basketball but in the opposite direction move backward at a higher speed than the basketball moves forward have the same forward momentum as the basketball

Inertia Mass A reaction force A gravitational force 11. A child jumps on a trampoline, as shown above. Which of the following causes the child to rise in the air? Inertia Mass A reaction force A gravitational force

Inertia Mass A reaction force A gravitational force 11. A child jumps on a trampoline, as shown above. Which of the following causes the child to rise in the air? Inertia Mass A reaction force A gravitational force

12. The pictures show how an air bag functions in a collision 12. The pictures show how an air bag functions in a collision. How much momentum in kg m/s does the air bag absorb from the crash-test dummy if all the crash-test dummy’s momentum is absorbed by the air bag? Record and bubble in your answer to the nearest whole number on the answer document.

12. The pictures show how an air bag functions in a collision 12. The pictures show how an air bag functions in a collision. How much momentum in kg m/s does the air bag absorb from the crash-test dummy if all the crash-test dummy’s momentum is absorbed by the air bag? Record and bubble in your answer to the nearest whole number on the answer document. 100 kg x 6.3 m/s = 630 kg m/s

13. How many newtons of force does a 50 13. How many newtons of force does a 50.0 kg deer exert on the ground because of gravity? Record and bubble in your answer on the answer document.

13. How many newtons of force does a 50 13. How many newtons of force does a 50.0 kg deer exert on the ground because of gravity? Record and bubble in your answer on the answer document. 50.0 kg x 9.8 m/s2 = 490 N