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Forces and Energy Review
Define Key Terms
Mass: The amount of matter an object has.
Gravity: The force of attraction between objects that is due to their mass
Friction: A force that opposes motion between two surfaces that are in contact.
Weight: The mass of an object with respect to gravitational pull.
Speed: The distance traveled divided by the time interval during which the
motion occurred.
Velocity: The speed of an object in a particular direction.
Force: A push or pull that acts on an object.
Acceleration: The rate at which the velocity changes over time (change in speed
or direction).
Inertia: A property of matter that opposes a change in motion until an outside
force acts on it.
Kinetic Energy: Energy based on the motion of an object
Potential Energy: Energy based on the position of an object
Law of Conservation of Energy: Energy cannot be created or destroyed.
UNDERSTANDING KEY IDEAS
Short Answer
11. Describe the relationship between motion and a reference point.
An object is said to be in motion if it changes position relative to a reference
point.
12. How is it possible to be accelerating and traveling at a constant speed?
An object would be changing direction.
13. Explain the difference between mass and weight.
Mass is the amount of matter in an object, and weight is dependant on the pull of
gravity.
14. What would you need to calculate an object’s average acceleration?
Initial velocity, Final Velocity, time it took to reach final velocity
15. What two ways can you increase gravitational pull between two objects (law of
gravitational force)?
Increase mass of the objects or decrease the distance between the objects.
16. What unit is used to measure forces?
Newtons named after Issac Newton
17. What is the difference between average speed and instantaneous speed? How do you
measure average speed?
Average speed is the general speed over a distance and instantaneous speed is at
one specific moment. Average speed is calculated by take the total distance
traveled and dividing it by the time it takes to travel that distance.
18. Explain the difference between balanced and unbalanced forces.
A balanced force is what the net force on an object is 0 N. An unbalanced force is
when the net force is anything other than 0 N, and therefore a movement.
19. Why is there friction between surfaces?
All surfaces have bumps at some level(may be microscopic) and so objects get
interlocked in one another causing an opposition to movement.
20. What is transferred from one object to the next when one hits the other?
Energy is transferred from one object to the next.