Podcast
Questions and Answers
In which scenario is the net force acting on an object equal to zero?
In which scenario is the net force acting on an object equal to zero?
- A car accelerating from rest.
- A skydiver accelerating downwards.
- A ball rolling down a ramp.
- A book resting on a table. (correct)
Which of the following best describes a free-body diagram?
Which of the following best describes a free-body diagram?
- A diagram showing all forces acting on a system. (correct)
- A diagram showing the internal forces within an object.
- A diagram showing the motion of an object over time.
- A diagram showing only the gravitational force acting on an object.
How does the length of an arrow in a free-body diagram relate to the force it represents?
How does the length of an arrow in a free-body diagram relate to the force it represents?
- The length is inversely proportional to the magnitude of the force.
- The length is arbitrary and does not represent any physical quantity.
- The length is proportional to the magnitude of the force. (correct)
- The length indicates the direction of the force, not the magnitude.
What is the relationship between action and reaction forces according to Newton's Third Law?
What is the relationship between action and reaction forces according to Newton's Third Law?
When analyzing forces, how is Earth typically treated when considering a small object interacting with it?
When analyzing forces, how is Earth typically treated when considering a small object interacting with it?
What is the proper unit to measure weight?
What is the proper unit to measure weight?
What term describes the support force exerted on an object, such as a scale exerting a force on a person?
What term describes the support force exerted on an object, such as a scale exerting a force on a person?
How does the apparent weight of an object compare to its real weight when the object is in an elevator accelerating upwards?
How does the apparent weight of an object compare to its real weight when the object is in an elevator accelerating upwards?
You are holding a 1-kilogram mass suspended from a spring scale inside an elevator. If the scale reads 9.3 N, what can be inferred about the elevator's motion?
You are holding a 1-kilogram mass suspended from a spring scale inside an elevator. If the scale reads 9.3 N, what can be inferred about the elevator's motion?
Under what condition are the apparent and real weights of an object the same?
Under what condition are the apparent and real weights of an object the same?
An object in equilibrium in a coordinate system has vectors acting on it. For angles less than $90°$ and greater than $270°$, which of the following is correct?
An object in equilibrium in a coordinate system has vectors acting on it. For angles less than $90°$ and greater than $270°$, which of the following is correct?
Which statement accurately describes the relationship between a vector and its components?
Which statement accurately describes the relationship between a vector and its components?
If you walk 8.0 km north and then walk east until your displacement from home is 10.0 km, approximately how far east did you walk?
If you walk 8.0 km north and then walk east until your displacement from home is 10.0 km, approximately how far east did you walk?
In a tug-of-war, one team ties their end of the rope to a tree while the other team pulls with a 500 N force. Assuming the rope is in equilibrium, what is the tension in the rope?
In a tug-of-war, one team ties their end of the rope to a tree while the other team pulls with a 500 N force. Assuming the rope is in equilibrium, what is the tension in the rope?
Two horizontal forces are exerted on a large crate. One force is 317 N to the right and the other is 173 N to the left. If the crate is initially at rest and, after five seconds, its velocity to the right is 6.5 m/s, what is the crate's mass?
Two horizontal forces are exerted on a large crate. One force is 317 N to the right and the other is 173 N to the left. If the crate is initially at rest and, after five seconds, its velocity to the right is 6.5 m/s, what is the crate's mass?
Flashcards
Free-Body Diagram
Free-Body Diagram
A physical representation showing forces acting on a system. Drawn separately, uses particle model, shows force vectors.
Net Force
Net Force
The vector sum of all forces acting on an object.
Apparent Weight
Apparent Weight
The support force exerted on an object.
Weight
Weight
Signup and view all the flashcards
Gravitational Field
Gravitational Field
Signup and view all the flashcards
Newton's Third Law
Newton's Third Law
Signup and view all the flashcards
Interaction Pair
Interaction Pair
Signup and view all the flashcards
Study Notes
- Grade 9 - Term 2 End of Term 2 Exam Coverage 2024-2025 Part 1
Free-Body Diagrams
- A free-body diagram is a physical representation showing the forces acting on a system.
- Free-body diagrams are drawn separately from the sketch of the problem situation.
- The object is represented as a dot.
- Forces are represented with arrows pointing in the direction of the force, drawn away from the dot.
- The length of arrows is proportional to the size of the force.
- Forces are labeled with the symbol F and a subscript label to identify the agent and the object.
- A direction must be chosen to be positive and is indicated in the diagram.
Combining Forces
- Forces in the same direction can be summed to form a resulting force.
- Forces in opposite directions are combined by taking the difference between them.
- The vector sum of all the forces on an object is the net force.
- If the net force is zero, then the forces are balanced, and there is no acceleration.
- If the forces are unbalanced, there will be acceleration.
Skydiver and Softball Examples
- For a skydiver falling at a constant velocity, the force of air resistence on the diver equals the force of Earth's mass on the diver, indicated by Fnet = 0.
- When holding a softball, the hand on ball contact force equals the Earth's mass on ball gravity force.
- After a softball leaves a hand it will rise and slow down.
- After the softball reaches maximum height it will falls down and speed up.
Connecting Interaction Pairs and Newton's Third Law
- Forces always come in pairs.
- An interaction pair is a set of two forces that are in opposing directions, have equivalent magnitude and act on different objects
- Newton's Third Law states that all forces come in pairs.
- The two forces in a pair act on different objects, are equal in strength, and are opposite in direction.
- With forces like Earth's mass on a ball, and a ball on Earth's mass, the Earth's acceleration is negligibly small due to the large mass of the Earth compared to small objects.
- If you lift a bowling all your hand exerts a force on the ball, and the Earth exerts a gravitational force on the ball. and the ball exerts a force on your hand and a gravitational force on Earth.
- A suitcase on a cart has a gravitational force of the Earth on the suitcase, and the surface of the cart exerts a force on the suitcase. The suitcase force on the cart, and the suitcase on the Earth.
- When a ball is tossed in the air, after it loses contact with a hand, the Earth's mass is the acting force on the ball.
Apparent Weight
- Apparent weight is the support force exerted on an object.
- Weightlessness means there are no contact forces supporting the object, so apparent weight is zero.
- When traveling at a constant velocity the apparent weight and real weight are equal.
- Apparent weight is less than real weight when the velocity is slowing while rising, or speeding up while descending.
- Apparent weight is greater than real weight when the velocity is speeding up while rising, or slowing while descending.
- When a scale is read at a different weight than the object's weight, there is an acceleration of the elevator
- At a constant velocity, the scale's weight will read the objects mass times gravity.
Formula for Weight
- Weight is defined as the gravitational force on an object, given by F = mg , where m is the object's mass and g is the gravitational field (9.8 N/kg on Earth).
Combining Forces
- To solve for the force on a crate that has one force of 317N to the right, and 173 N to the left the equation used is Fnet = 317 N -173 N
Solving Vector Problems
- To solve a vector problem the components must be calculated.
- To solve for displacement you must first calculate the components, and then use the components in the Pythagorean Theorem.
- A vector can be shorter, but never longer than its components.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
