BELLWORK 3-18-15 WHICH EXAMPLE BEST DEMONSTRATES NEWTON’S FIRST LAW OF MOTION?

A) THE GROUND PUSHES UP WITH THE SAME FORCE WITH WHICH A BASKETBALL PLAYER PUSHES DOWN.

B) THE LEAVES OF A TREE DO NOT MOVE UNTIL WIND BLOWS ON THEM.

C) A TENNIS BALL ACCELERATES MORE THAN A BOWLING BALL WHEN EQUAL FORCES ARE APPLIED TO EACH.

D) A BASEBALL BAT BREAKS WHEN A BATTER HITS A BALL.

OBJECTIVE

• Can I identify and explain how Newton’s laws of motion relate to the movement of objects?

TO REVIEW, SOMEONE EXPLAIN IN THEIR OWN WORDS….

• Newtons’s 1st Law

• Newton’s 2nd Law

NEWTON’S THIRD LAW OF MOTION

•Newton’s third law can be simply stated as follows: All forces act in pairs.

For every action there is an equal and opposite reaction.

NEWTON’S 3RD LAW OF MOTION

BACK TO NEWTON’S 1ST LAW…FRICTION

• Friction is a force that opposes motion between two surfaces that are in contact.

• Friction created between the bristles of the sponge and the dish can remove food.

• Friction can cause a moving object, such as a ball, to slow down and eventually come to a stop.

•With your elbow partner, come up with your own example/scenario of friction.

NEWTON’S 1ST LAW, AGAIN…GRAVITY

• Gravity is a force of attraction between objects that is due to their masses. The force of gravity can change the motion of an object by changing its speed, direction, or both.

• Objects fall to the ground at the same rate because the acceleration due to gravity is the same for all objects. Why is this true? Acceleration depends on both force and mass. A heavier object experiences a greater gravitational force than a lighter object does. But a heavier object is also harder to accelerate because it has more mass.

BACK TO NEWTON’S 2ND LAW:MOMENTUM

• Imagine a compact car and a large truck traveling with the same velocity. The drivers of both vehicles put on the brakes at the same time. Which vehicle will stop first?•The car because a larger force is needed to stop the truck. The truck has more momentum because it has more mass.•The momentum of an object depends on the object’s mass and velocity. The more mass an object has, the more momentum it has.

BACK TO NEWTON’S 1ST LAW…FRICTION

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EXIT TICKET

• Work on Newton’s 3rd law comic strip