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Science CBA #2 Review

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**Force and Motion What is motion?**

Motion is when an object changes its position. Motion can be represented mathematically through calculations of speed, velocity, and acceleration

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Velocity Velocity has speed and direction. Velocity = distance + direction time

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Displacement Displacement is the distance and direction between the starting and ending position. A car moved 60 km East and 90 km West. What is the distance? What is the total distance? __________ ___ What is the displacement? __________ ___

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**A bike rider biked 50 km North and 30 km South**

A bike rider biked 50 km North and 30 km South. What is the displacement? What is the total distance? __________ ___ What is the displacement? __________ ___

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#1 Velocity Later that day, they decided to work on their fitness and go run the track. They headed 60 meters southwest from their rooms to the track which took them 20 seconds. What is their velocity? v = d+direction t

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#1 Velocity Answer d = 60 m SW t = 20 sec v = ? v = 60 m SW 20 sec v = 3 m/sec/SW

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Speed The distance an object travels in a certain amount of time. Average speed – Total distance divided by total time Constant speed - Speed that does not change

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**What is the formula for calculating speed?**

Speed equals distance divided by time. Speed = Distance ÷ Time Create the triangle

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Speed Problem A football field is about 100 meters long. If it takes a person 20 seconds to run its length, how fast was the football player running?

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Speed Problem Answer Speed = Distance ÷ Time Speed = 100 m ÷ 20 s Speed = 5m/s

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Acceleration A change in the direction or speed (velocity) of an object over time – which may be: -A change in speed Starting Stopping Speeding up (positive acceleration) Slowing down (negative acceleration) -A change in direction Acceleration is caused by unbalanced forces

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Unit for Acceleration m/s s Unit for Acceleration km/hr s

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If a car is moving on a road at 70 km/hr going due north, and then changes direction and starts traveling northeast staying at 70 km/hr, what happens to its speed and velocity? A The speed of the car changes, but the velocity stays the same. B The velocity of the car changes, but the speed stays the same. C Both the speed and velocity of the car change. D Neither the speed nor the velocity of the car changes.

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**A 2000 kg truck and a 500 kg car are racing**

A 2000 kg truck and a 500 kg car are racing. The same amount of force is applied to each of them. What will happen? A The truck will accelerate twice as fast. B The car will accelerate twice as fast. C The truck will accelerate four times as fast. D The car will accelerate four times as fast.

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Martin gathered a toy car, a ramp, a stopwatch, a meter stick, and a variety of weights. What is he likely testing? A how the angle of a ramp affects the speed of the car B how friction affects the speed of the car C how equal forces work on the placement of the car and the ramp D how mass affects the speed of the car

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Practice What is the speed of a train that runs 4200 km in 21 hours? s=d/t

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Practice s= 4200/21 s= 200 km/hr

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Practice Two people head 60 meters southwest and it took them 20 seconds. What is their velocity v= distance+ directions time *remember velocity is speed and direction

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Practice d= 60 m sw t= 20 sec s=? v= 60/ 20 v= 30 m/s sw

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**Force The cause of motion (what causes objects to move)**

Force has four components: push, pull, size, and direction Force always come in pairs. It’s impossible to have only one force

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**Forces are measured in Newtons**

Symbol: N •Measured by using a spring scale •What is a newton? A newton is a force required to accelerate a one kg mass at a rate of one m/s2.

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Net Force Net Force: Net force is the sum of all the forces acting on an object •If the forces are in the SAME direction, then you add them together. 5 N > 5 N > •If the forces are in opposite directions then you subtract the smaller force from the larger force. 10 N ------> < 5 N

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**Forces may be balanced or unbalanced**

Balanced forces – all forces acting on an object are equal –There is NO MOTION •Unbalanced forces – one or more forces acting on an object are stronger than others –There is MOTION •A NET FORCE

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Balanced Forces Balance force describes forces that are equal but opposite in direction; when they act on an object, they cancel each other out and no change occurs in the object’s motion.

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Unbalanced •Unbalanced forces describe unequal forces acting on an object. This results in a change in the object’s motion in the direction of the larger force.

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Newton’s Laws Review CBA

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**What is the formal name for Newton’s 1st Law?**

The Law of Action/Reaction The Law of Inertia The Law of Force and Acceleration

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**Which law states that “for every action, there is an equal and opposite reaction”?**

Newton’s 1st Law Newton’s 2nd Law Newton’s 3rd Law

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**What is the formal name for Newton’s 2nd Law?**

The Law of Action/Reaction The Law of Inertia The Law of Force and Acceleration

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Which law states, “an object acted on by an unbalanced force will accelerate in the direction of the force”? Newton’s 1st Law Newton’s 2nd Law Newton’s 3rd Law

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**What is the formal name for Newton’s 3rd Law?**

The Law of Action/Reaction The Law of Inertia The Law of Force and Acceleration

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Which law states, “an object in motion tends to stay in motion and an object at rest tends to stay at rest until acted upon by an unbalanced force”? Newton’s 1st Law Newton’s 2nd Law Newton’s 3rd Law

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**A book is sitting on the table at rest**

A book is sitting on the table at rest. The forces acting on the book include _______, and these forces are _______. Gravity pushing down and the table pushing up; balanced Gravity pushing down and the table pushing up; unbalanced Gravity pushing up and friction pushing to the right; balanced

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**Tom is teaching Jenny how to ice skate**

Tom is teaching Jenny how to ice skate. Both skaters, who are about the same size, are on the ice and wearing their skates. To help Jenny get started, Tom gives her a gentle push from behind. Which of the following best describes what will happen next? Jenny will move backward; Tom will move forward Jenny will move forward Jenny will move forward; Tom will move backward

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**What are the four components of force?**

Push, Pull, Speed, Direction Push, Size, Speed, Direction Push, Pull, Size, Direction

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**Which of the following best describes the difference between speed and acceleration?**

Acceleration is the distance an object travels within a specific unit of time; speed is the measure of the force necessary to change the acceleration of an object Speed is the distance an object travels within a specific unit of time; acceleration is a measure of the force necessary to change the speed of an object Speed is the distance an object travels within a specific unit of time; acceleration is the rate at which the speed or direction of an object is changing

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**How much force is needed to accelerate a 2,000 kg car at a rate of 8 m/s2?**

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Reggie accidentally left his books on top of his car before he left for class. The books stayed on top of his car while he was driving north on Oak Avenue. Then, when he made a sharp turn eastward onto Harris Lane, his books fell off the top of his car and onto the street. Which of the following best explains why Reggie's books fell? When Reggie's car turned eastward, his books continued heading northward, causing them to slide off the top of his car and fall. The Earth's magnetic field held the books on Reggie's car while he headed north. When he turned east, the magnetic pull faded, causing the books to fall. Heat energy from the Sun caused Reggie's books to slide off the top of his car and fall.

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**If Sara's father presses on the brakes quickly slowing the car down, what slows Sara down?**

the seat pushing forward on her her seat belt pulling back on her air resistance on the outside of the car

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**Jodie sets two objects on a flat surface**

Jodie sets two objects on a flat surface. Object A has a mass of 50g, while object B has a mass of 250g. Jodie pushes both objects with the same force and watches them accelerate. Which object will accelerate more? Object B accelerates more. Object A accelerates more. They accelerate the same amount.

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A car is traveling south at a speed of 65 miles per hour and then begins traveling west but continues traveling at the same speed. Which of the following has changed? Speed Mass Velocity

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**Two teams are playing tug-of-war**

Two teams are playing tug-of-war. Each team is pulling on the rope with a force of 500 newtons. A ribbon is tied to the middle of the rope to determine the winner. Which of the following would result in the greatest acceleration of the ribbon? A player added to Team B pulls on the rope with a force of 120 newtons. A player added to Team A pulls on the rope with a force of 130 newtons. A player on Team B who was pulling with a force of 150 newtons leaves the game.

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Newton's first law of motion states that an object will keep a constant velocity unless acted upon by an unbalanced force. To test this statement, Martin rolled a ball on a long, level street. The ball did not bump into any object, but it eventually came to a stop. How is this possible? Every moving object must come to a stop because energy cannot be destroyed. Martin did not roll the ball hard enough, which caused the ball to eventually stop rolling. The unbalanced force that caused the ball to stop was friction.

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**What is the definition of inertia?**

The tendency of a body at rest to stay at rest or of a body in motion to remain in motion. The tendency of an object in motion to decelerate. The rate at which an object accelerates.

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Plate Tectonics CBA

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**The theories of continental drift and sea-floor spreading combined to make the theory of _______.**

plate tectonics rejoined continents Pangaea

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The Atlantic Ocean is currently growing wider as its floor enlarges due to the process of sea-floor spreading. In sea-floor spreading, pieces of oceanic crust move sideways against each other along a transform plate boundary. move together along a convergent plate boundary. move apart along a divergent plate boundary.

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A tectonic plate applies a downward force onto the asthenosphere, which lies beneath the plate. According to Newton's 3rd Law, which can be described as the law of action-reaction, the asthenosphere applies a force of double magnitude upward onto the tectonic plate. the asthenosphere applies a force of equal magnitude upward onto the tectonic plate. the asthenosphere applies a force of equal magnitude downward as well.

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Where the river enters the lake, it branches into many channels and has deposited a large, fan-shaped feature extending out from the shore (marked by "X"). What is this feature? a sand dune a delta a barrier island

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A subduction zone is an area where one tectonic plate sinks underneath another one. Volcanoes often form as a result. Which of the following plate collisions would most likely result in a subduction zone? a piece of continental crust and a piece of oceanic crust meeting at a convergent boundary two pieces of oceanic crust meeting at a divergent boundary a piece of continental crust and a piece of oceanic crust meeting at a divergent boundary

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**Which of the following provides the most evidence for the theory of plate tectonics?**

the spreading of the sea floor the locations of the glaciers the changing of the seasons

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