7th Grade Gravity & Kinetic Energy Review

Topic: Gravity & Kinetic Energy Review

EQ: What will be on my Science Benchmark on Friday?

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Topic: Investigation 1 Acceleration

EQ: How are speed and acceleration alike and how are they different?

Investigation 1 Acceleration

• The average speed of an object is the distance it travels in a unit of time (v = ∆x/∆t).

• The slope of the line on a graph of distance versus time represents the speed; steeper slopes represent faster speeds. 

• An object that does not move at a constant speed has acceleration, change of speed per unit time (a = ∆v/∆t).

Investigation 1 Acceleration

• A falling object increases speed with a constant acceleration, regardless of the object’s mass.

• Gravity is an attractive force between two objects with a rate of acceleration of 9.8 m/s2 on Earth.

Multiple Choice

Which of the runner's is accelerating?

• Runner A

• Runner B

• Runner C

• Runner D

Multiple Choice

What is the average speed of the object? 

 $Speed\ =\ \frac{Dis\tan ce}{Time}$  

• 0.5 meters/ minute 

• 2 meters/ minute 

• 2.5 meters/ minute 

Multiple Choice

What is the average speed of Object B (solid line) at 10 seconds?

• 3 m/s

• 6 m/s

• 15 m/s

Multiple Choice

Which car is going the slowest?

• Car 1

• Car 2

• Car 3

• Car 4

Multiple Choice

Use the data table. Which car traveled the farthest?

• Car A

• Car B

• Car C

• Car D

Topic: Investigation 2 Force of Gravity 

EQ: How can we describe gravitational force?

Topic: Investigation 2 Force of Gravity 

• Gravity is an attractive force between two objects.

• Mass is the amount of matter in an object.

• Weight is the force of gravity on an object.

Investigation 2 Force of Gravity 

• The acceleration of an object increases if the force acting upon it increases (F = ma).

• If identical force is applied to two objects with different masses, the more massive object will accelerate less than the less massive object (F = ma)

Multiple Choice

Which statement best states the relationship between mass and gravitational attraction between two objects?

• The less mass an object has, the greater its gravitational force.

• The more mass an object has, the greater its gravitational force

• The masses of objects do not aect gravitational force.

Multiple Choice

If a wagon is accelerating at a rate of 2 m/s2 and the force acting on it is 20 N, what is the mass of the wagon?

 $Mass\ =\ Force\ \div\ Acceleration$  

• 0.1 kg 

• 10 kg 

• 4 kg 

• 40 kg 

Multiple Choice

A ball rolls slowly to the edge of a building’s roof. Which of the following best describes the ball’s motion after it passes the edge of the roof?

• The ball falls at a constant speed of about 1 meter per second per second.

• The ball falls at a constant speed of about 10 meters per second.

• The ball falls with a speed that increases by about 1 meter per second.

• The ball falls with a speed that increases by about 10 meters per second per second.

Multiple Choice

A bag of potatoes has a mass of 2.5 kilograms (kg). What is its approximate weight on Earth?

Force = mass x acceleration

Acceleration of gravity on Earth = 10 meters/second/second

• 25 Newtons

• 25 Pounds

• 25 Calories

• An object's mass is the same as its weight.

Topic: Investigation 3 Energy and Collisions 

EQ: What factors affect collision events?

Investigation 3 Energy and Collisions 

• Kinetic energy is energy of moving things; potential energy is energy dependent on the position of an object.

• A collision transfers kinetic energy.

• Increasing the mass of an object by some factor increases its kinetic energy by the same factor; increasing the speed of an object by some factor increases its kinetic energy by the same factor squared.

Investigation 3 Energy and Collisions 

• An object in motion will stay in motion with the same speed (or a still object will stay still) unless acted on by an external force

• For every action, there is an equal and opposite reaction.

Newton's Laws of Motion

• Newton’s First Law of Motion: Every object stays at rest unless an outside force acts on it. If an object is moving, it travels in a straight line at a constant speed unless an outside force acts on it.

• Newton’s Second Law of Motion: The acceleration of an object is directly proportional to the force of the object. It is inversely proportional to its mass (a=F/m, or F=ma).

• Newton’s Third Law of Motion: For every action or force, there is an equal and opposite reaction or force. 

Multiple Choice

A bowling ball is rolling down a ramp with a certain amount of kinetic energy. Which change to the system will increase the ball’s kinetic energy most?

• Doubling the weight of the bowling ball

• Doubling the mass of the bowling ball

• Doubling the speed of the bowling ball

• Doubling the volume of the bowling ball

Multiple Choice

A motor boat is traveling 10 m/s on a sunny calm day. The driver turns o the engine. Apply Newton’s first law to explain what happens to the boat as it glides through the water

• The boat moves slower and slower.

• The boat moves at a constant speed.

• The boat moves at constant speed for a while and then slows down.

• The boat slows down for a while and then moves at constant speed.

Multiple Choice

A teacher throws a tennis ball straight up into the air. At what point does the ball have the most POTENTIAL energy?

• Right after the ball leaves the teacher’s hand

• As the ball begins to slow down

• Just before the ball hits the ground

• When the ball is at its highest position

Multiple Choice

A teacher throws a tennis ball straight up into the air. At what point does the ball have the most KINETIC energy?

• Right after the ball leaves the teacher’s hand

• As the ball begins to slow down

• Just before the ball hits the ground

• When the ball is at its highest position

Multiple Choice

Two students are playing on a teeter-totter during recess. Which one has more potential energy?

• Student A has more potential energy.

• Student B has more potential energy.

• They have the same amount of potential energy.

• More information is needed to determine which student has more potential energy.

Multiple Choice

Two children are sledding down a hill. Child X is 7 centimeters taller than child Y, but they both weigh the same, and both of their sleds weigh the same. If they are sledding at the same speed, which one has more kinetic energy?

• Child X has more kinetic energy.

• child Y has more kinetic energy.

• Both of them have the same amount of kinetic energy.

• More information is needed to determine which child has more kinetic energy.

Multiple Choice

Two balls are rolling down a hill at the same speed. Which ball has more kinetic energy?

• Ball 1 has more kinetic energy.

• Ball 2 has more kinetic energy.

• Both balls have the same amount of kinetic energy.

• More information is needed to determine which ball has more kinetic energy.

Homework- STUDY FOR YOUR BENCHMARK!

• Complete your Cornell Notes using our Benchmark Review on Quizizz.

• Study for your benchmark!!!!

• All late work is due by April 23rd at 3PM

• Last day of MP3 is April 23rd