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Definitions 1
Definitions 2
Questions 1
Questions 2/ NJ Ask Prep 1
NJ Ask Prep 2
100
What is acceleration? What is inertia?
Acceleration is a change in an object's speed or direction; acceleration= change in velocity/change in time. Inertia is the tendency of objects to keep doing what they are doing (moving or staying at rest).
100
What is net force?
Net force is the amount by which the opposing forces acting on an object are unequal.
100
Gabe kicked a soccer ball across a field. The ball rolled for a while but eventually stopped. If Newton's first law is true, it seems that the ball Gabe kicked should continue rolling forever. Why does the ball stop? Suppose you are playing baseball and hit a home run. What forces slow down the ball while it is in motion? If you hit the home run in outer space, what would happen.
The ball stops because friction causes a slow down. Friction is an unbalanced force. Friction and gravity would slow down the baseball when in motion on Earth. If the ball is hit in outer space it would move in a straight line at a constant speed until it came under the influence of gravity from another body such as a star or planet.
100
Use the formula for slope to find the speed of the object in the graph on page 112 in the New Jersey Buckle Down Workbook. On page 113 in the New Jersey Buckle Down Workbook there is a graph. Use this graph to determine the slope of the line between 4 s and 6 s. What does this say about the objects speed?
50-0/5-0 = 50/5 = 10m/s. 50-50/6-4 = 0/2 = 0m/s, this means that the slope is constant.
100
Sean pushes a parked car with a force of 80 newtons (N)> The car does not move. Describes the force that the car exerts on Sean.
The same amount of force as Sean exerts.
200
What is contact force?
Contact force is a force that must touch an object to change its speed and/or direction.
200
What is a newton?
Newton is the metric unit to measure force or weight.
200
Suppose that Sharon rides her bike at a speed of 10m/s. As she rides up a hill, her speed decreases to 5m/s. Is her acceleration positive or negative? Now, suppose Sharon rides her bike down the street in 20 seconds. Durning this time, her speed remains constant at 5m/s. What is the value of her acceleration during this time?
Sharon's acceleration is negative because she is going against gravity. Acceleration is 0m/s squared (N).
200
Identify all of the time intervals when the object is speeding up, slowing down, or keeping a constant speed. Identify the speed of the object between 20 and 4 s.
Speeding up between 0-20 and 4-50, slowing down between 60-80, and constant at 20-40 and 50-60 Speed=20m/s
200
What force has the greatest influence on the structure of solar systems and galaxies?
Gravity
300
What is force?
Force is a push or pull that causes something to change its motion.
300
Describe Newton's first, second, and third law of motion.
Newton's first law of motion is when the forces acting on an object are balanced, the object will continue doing what is is doing. Newton's second law of motion is when the acceleration of an object is related to the net force acting on it and the mass of an object: F=ma Newton's third law of motion is when for every action, there is an equal and opposite reaction.
300
Give an example of a situation in which you apply a force to something and it goes faster, goes slower, and changes direction. Dave is driving down the street. If Dave steps on the brakes, what force slows in car. What force causes a ball to speed up as it rolls down a hill?
When a bike goes down a hill it "goes faster". WHen riding a bike up hill it "goes slower". When a kite blows back and forth in the wind it "changes direction". Friction between the car's tires and the road cause the car to stop. Gravity causes a ball to speed up as it rolls down hill.
300
What is an example of contact force?
Friction.
300
Zach throws a ball straight up into the air. The height of the ball at different times in shown in the table on page 118 in the New Jersey Buckle Down Workbook. What i the average speed of the ball from 3 s to 4 s?
15 m/s.
400
What is friction?
Friction is a force that occurs when two things move past each other and rub together.
400
What is noncontact force?
Noncontact force is a force that acts on an object to change it's speed or direction from a distance.
400
Sharon cruises east at 7m/s. She then uses her brakes and comes to a gentle stop. As Sharon slows, how does the direction of the net force compare to that of her motion.
The net force is west, opposite the direction of her motion.
400
What is a situation where the forces acting on an object are balanced.
A hot-air balloon rises at a constant speed.
400
In outer space, a small ball of rock and ice travels for thousands of years. Its motion does not change in any way during that time. As it approaches the solar system, however, it comes under the influence of the Sun's gravity, and its motion begins to change. Which principle does this demonstrate?
An object in motion moves in a straight line at constant speed until acted on by a net force.
500
What is gravity?
Gravity is a force that acts without physical contact to pull two objects toward each other.
500
What is normal force?
Normal force is the force that pushes up to support the weight of an object.
500
Think back to the story of Alicia and the soccer ball.Using Newton's third law of motion, explain how she could kick the ball into the goal.
Alicia exerts a force on the ball and the ball exerts an equal and opposite force on her. Alicia has a greater mass than the ball so the balls motion changed, but Alicia's motion did not change.
500
The net force acting on an object is 0 N. Best describe the motion of the object.
The objects motion is not changing.
500
Tamara rode her bike to her friend's house. The distance-time graph shown on page 118 in the New Jersey Buckle Down Workbook represents Tamara's trip. Describe Tamara's speed and the net force acting on her bicycle between 15 minuets and 20 min. Include proper units.
Her speed is constant.