Want to retake Quiz 8 FBD's? Today at nutrition or lunch
Today is the first day of Newton's 3rd Law. You should be very familiar with the 1st and 2nd laws by now
The warm up and practice problem today on Newton's 2nd problem solving should help you determine what you need to review for Monday's quiz.
#Goals: SWBAT...
1. Use FBD's to find Net Force
2. Solve for forces using mass, net force, and acceleration
3. Define Newton's 3rd law
Warm-Up (4min)
Read the scenario below, then answer the questions at the end
"Lee Mealone is sledding with his friends when he becomes disgruntled
by one of his friend's comments. He exerts a rightward force of 9.13 N
on his 4.68-kg sled to accelerate it across the snow. If the acceleration
of the sled is 0.815 m/s/s, then what is the coefficient of friction between
the sled and the snow?"
List the forces present in this example
Draw the FBD
Which equations would you use in your process to find the coefficient
of friction (µ)
CLASSWORK
1. #050A: Practice with Solving FBD's
A. find the coefficient of friction for the warm-up problem
B. In a Physics lab, Ernesto and Amanda apply a 34.5 N rightward force to a
4.52-kg cart to accelerate it across a horizontal surface at a rate of 1.28 m/s/s.
Determine the friction force acting upon the cart.
2. #050B: Newton's 3rd
For every force applied by an object, there's an equal and opposite force
on that object.
Notes: link
Edpuzzle: EDpuzzle
3. #050C: Identifying Interaction Pairs
1. While driving down the road, a firefly strikes the windshield of a bus and makes a quite obvious mess in front of the face of the driver. This is a clear case of Newton's third law of motion. The firefly hit the bus and the bus hits the firefly. Which of the two forces is greater: the force on the firefly or the force on the bus?
2. For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. This inability of a rocket to provide propulsion is because ...
a. ... space is void of air so the rockets have nothing to push off of.
b. ... gravity is absent in space.
c. ... space is void of air and so there is no air resistance in space.
d. ... nonsense! Rockets do accelerate in space and have been able to do so for a long time.
a. greater than the acceleration of the bullet.
b. smaller than the acceleration of the bullet.
c. the same size as the acceleration of the bullet.
4. In the top picture (below), Kent Budgett is pulling upon a rope that is attached to a wall. In the bottom picture, Kent is pulling upon a rope that is attached to an elephant. In each case, the force scale reads 500 Newton. Kent is pulling ...
a. with more force when the rope is attached to the wall.
b. with more force when the rope is attached to the elephant.
c. the same force in each case.
Read the following, and list all the interaction pairs you find:
A variety of interaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). Interaction force pairs make it possible for fish to swim.
Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from mutual interactions, the air must also be pushing the bird upwards. The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). For every action, there is an equal (in size) and opposite (in direction) reaction. 3rd Law force pairs make it possible for birds to fly.
Consider the motion of a car on the way to school. A car is equipped with wheels that spin. As the wheels spin, they grip the road and push the road backwards. Since forces result from mutual interactions, the road must also be pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards). For every force, there is an equal (in size) and opposite (in direction) simultaneous force. 3rd Law force pairs make it possible for cars to move along a roadway surface.
At Home Learning (HW)
Complete all of the above...
#050E: Edpuzzle Video: https://edpuzzle.com/media/5808f3259935d0833a0236e3
NGSS Standard (this is what we're learning with this unit)
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship amongthe net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object sliding down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]
NGSS Standard (this is what we're learning with this unit)
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship amongthe net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object sliding down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]
#GOALS: SWBAT....
1. Use FBD's to find Net Force, mass, acceleration
2. Use mu and Fn to find Ff.
3. Explain the relationship between mass, Fn, and the behavior of a horizontally moving object
WARM-UP
A rightward force is applied to a 5-kg object to move it across a rough surface with a rightward acceleration of 2 m/s/s. The coefficient of friction between the object and the surface is 0.1. Use the diagram to determine the gravitational force, normal force, applied force, frictional force, and net force. (Neglect air resistance.)
CLASSWORK
1. #050A: Practice
A rightward force of 25 N is applied to a 4-kg object to move it across a rough surface with a rightward acceleration of 2.5 m/s/s. Use the diagram to determine the gravitational force, normal force, frictional force, net force, and the coefficient of friction between the object and the surface. (Neglect air resistance.)
2. #050B: Newton's Second Law Predictions
The goal of this activity is for you to predict the effect of varying net force and varying mass upon the acceleration of an object. There are 12 different situations to analyze and three ability levels. Each situation involves requires that you use proportional reasoning and Newton's Second Law equation in order to determine the acceleration that results when the net force and/or the mass of the object is altered.
Either complete Apprentice and Master, OR complete Wizard. Either way, it's 12 questions. Write your answers in your notes like this:
#1 Q: Double acceleration, same mass A: Double force
3. FBD Quiz Corrections:
If you didn't take our FBD quiz last friday, you'll need to step out of the room
LEARNING AT HOME (HW)
#050C: Newton's 3rd Law
Edpuzzle: https://edpuzzle.com/media/5808f1e80ab906373fe9629b
Goals: SWBAT...
1. Momentum - Is It Conserved?
Warm-Up (5min):
No HW/video check today. Lots of fun lab work to do today though!
Golf. When a golf club hits a golf ball, which experiences a larger force?
Pool. When a cue ball hits the 8-ball, which experiences a larger force?
Figure Skating: Consider the interaction between a male and female figure skater in pair figure skating. A woman (m = 45 kg) is kneeling on the shoulders of a man (m = 70 kg); the pair is moving along the ice at 1.5 m/s. The man gracefully tosses the woman forward through the air and onto the ice. The woman receives the forward force and the man receives a backward force. Which force is larger? Who experiences a larger velocity change?
CLASSWORK
1. #050A: Momentum Notes. What Happens When Two Objects Interact?
Scenario: The dropped brick is at rest and begins with zero momentum. The loaded cart (a cart with a brick on it) is in motion with considerable momentum. )The actual momentum of the loaded cart can be determined using the velocity (often determined by a ticker tape analysis) and the mass.)
1. What happens to the x-velocity of the loaded cart after the dropped brick falls on it?
2. What happens to the x-velocity of the dropped brick after it falls on the cart?
3. What happens to the horizontal momentum of the cart during the collision?
4. What happens to the horizontal momentum of the dropped brick during the collision?
#050B: Activity: Is Momentum Conserved?
All data is in reference to the horizontal. Ignore the vertical velocity of the dropped brick.
You likely know the answer, but how could you use data to prove it?
Work by yourself or in a small group (2-3 total)
Choose two trials to analyze
Record data in pencil. Do any math NEATLY on a separate sheet of paper, and staple it to the handout.
Two or more people should do math INDEPENDENTLY, then compare answers.
Data is due tomorrow.
Absent? Link to handout is here: LINK
Link to activity is here: LINK
At Home Learning (HW)
1. complete #050B
Stuck? Here are two videos to help you through the process.
Measuring displacement and time
Use the remind app for any further questions...
Quiz 6: FBD's
draw object. label forces. use appropriate size force vectors.
A force is applied to the left to drag a cooler across loosely packed sand with a leftward acceleration. Neglect air resistance. Diagram the forces acting upon the cooler.
A baseball is moving upwards towards its peak after having been hit by the batter. Neglect air resistance. Diagram the forces acting upon the baseball as it rises upward towards its peak.