Newton’s Laws of Motion & Acceleration JEOPARDY An object’s inertia is dependent on this. Its mass Seatbelts reduce force by increasing stopping time therefore decreasing what? Acceleration F=mxa if “a” is smaller, then Force is smaller. A seatbelt acts as the unbalanced force stopping your forward motion due to what? Inertia If acceleration stayed constant and mass increased, what would happen to the Force? Force increases A construction worker lifts a 45-kg bundle of shingles on his shoulder at an acceleration of 3 m/s². How much force is he using? 135 N of force A golf ball is still on top of a tee. Mr. Feys hits it and it flies into the pond. Mr. Feys’ swing is considered this type of force. An unbalanced force A dragster racing down a road, a rocket launching and a balloon being let go in the classroom are ALL examples of this. Newton’s rd 3 Law of Motion or Unbalanced forces or Action/Reaction Forces A 500-kg car is using a force of 15,000 N to move. What is its acceleration? 30 m/s/s Mr. Ameel and his family went to Boyne Mountain for the weekend. They traveled in a straight line at 80 mi/hr at 0 acceleration (he used his cruise control). What was his net force on the car? 0 Newtons Because there was NO acceleration The mass and distance between two objects will determine this. The amount of gravitational force. This type of force will be felt when a car rounds a curve on the road or you ride a merry-go-round. Centripetal Force Mrs. Braniff threw a dodge ball at a person. She noticed that it followed a curved path before it hit. Explain what caused the ball’s curve to happen. The throw gave it a forward/horizontal motion and gravity gave it a downward/vertical motion. How much does a 45 kg person weigh on Earth? W= 45 kg x 9.8 m/s2 W = 441 N This would occur to an astronaut because the moon has less mass than the Earth. A person would weigh less. This type of force allows the moon to orbit around the Earth and the other planets to orbit around the Sun. Centripetal Force Mrs. Poloney drops a 15 LB rock and a 20LB from the roof of her house. Identify the rock that would cause the deepest hole when it hit the ground. The 20 LB rock due to its larger mass. An object in free fall would have this type of downward force. Gravity This object would have the LEAST amount of inertia. A. B. C. D. train sports car space shuttle bicycle A bicycle (less mass of all of the vehicles) A boat is using 6000 N of force to tow a skier with an acceleration of 12 m/s². Identify the skier’s mass. 500-kg Jack’s bike front tire hits a raised portion of the sidewalk causing him to flip over and hit the ground. Why???? Jack’s inertia or The bike stops & Jack’s body still moves forward or The crack is an unbalanced force If forces are unbalanced what will happen to an object? The object will accelerate. Why is rolling friction weaker than sliding friction? Less surface area touches when an object is on wheels therefore fewer microwelds form. According to Newton’s 3rd law of motion, if forces are equal in size and opposite in direction, why does motion occur? The forces don’t cancel, they act on different objects. When an object reaches terminal velocity, what happens to its motion? The object will fall with a constant velocity, it will stop accelerating. th 8 st 1 If an grader and a grader went sky diving, who would hit the ground first and why? th 8 The grader will hit the ground first because they reached a higher terminal velocity due to the larger mass. Balanced or Unbalanced? Balanced The car is NOT moving Balanced or Unbalanced? Unbalanced The tennis ball changes its motion when hit by the racket. STUDY!! The test is tomorrow!!