Newton's Laws of Motion
What are Newton's three laws of motion commonly known as?
The Law of Inertia, the Law of Acceleration, and the Law of Action-Reaction.
What are the two main types of friction studied in Dynamics?
Static friction and kinetic friction.
What is the force that pulls objects toward the centre of the Earth?
Gravitational force (weight).
What kinematics quantity describes how quickly an object's velocity changes?
Acceleration.
An astronaut pushes a spacecraft away from a space station. Why do both objects move, and which object experiences the greater acceleration?
Both objects experience equal and opposite forces (Newton's Third Law). The object with less mass experiences greater acceleration.
According to Newton's First Law, what happens to an object when the net force acting on it is zero?
It remains at rest or continues moving at a constant velocity.
What type of friction acts between two surfaces that are not sliding relative to one another?
Static friction.
What force acts perpendicular to a surface when an object is in contact with it?
Normal force.
If an object is moving at a constant velocity, what is its acceleration? What does this tell us about the net force?
Acceleration is zero, meaning the net force is zero.
Why can increasing the normal force increase the maximum static friction force between two surfaces?
Maximum static friction is proportional to the normal force:
Ff,max = ms*FN
According to Newton's Second Law, what happens to an object's acceleration if the net force increases while its mass stays constant?
Its acceleration increases proportionally.
What type of friction acts when two surfaces slide past one another?
Kinetic friction.
What is the name of the force transmitted through a rope, string, or cable when it is pulled tight?
Tension force.
What information from a velocity-time graph can be used to determine an object's acceleration?
The slope of the velocity-time graph.
An elevator is accelerating upward. How does the normal force exerted by the floor compare to the person's weight?
The normal force is greater than the person's weight.
Two objects experience the same net force. One has twice the mass of the other. Which object experiences greater acceleration?
The object with half the mass experiences twice the acceleration.
Why is it generally harder to get a heavy box moving than it is to keep it sliding once it is moving?
Maximum static friction is generally greater than kinetic friction.
What is the difference between an applied force and a normal force?
An applied force is exerted directly on an object by a person or another object. A normal force is exerted perpendicular to a contact surface.
A ball is thrown vertically upward. At the very top of its path, its velocity is zero. Is its acceleration also zero? Explain.
No. Its acceleration is still approximately 9.81 m/s² downward because gravity continues to act on it.
An elevator is accelerating downward. How does the normal force exerted by the floor compare to the person's weight?
The normal force is less than the person's weight.
A student pushes against a wall, but the wall does not move. According to Newton's Third Law, what force does the wall exert?
The wall exerts an equal-magnitude force in the opposite direction on the student.
A car suddenly brakes and its tires lock up. What type of friction acts between the tires and the road? How would this differ if the tires continued rolling without slipping?
Locked tires experience kinetic friction. Rolling tires without slipping experience static friction.
A box is being pulled across a horizontal floor using a rope at an upward angle. Identify the four forces acting on the box.
Gravitational force downward, normal force upward, tension/applied force diagonally upward, and kinetic friction opposing the motion.
Two cars are travelling at the same initial velocity. Car A accelerates twice as quickly as Car B. If both cars have the same mass, what can you conclude about the net forces acting on them?
Car A experiences twice the net force of Car B, according to Newton's Second Law.
A ball is dropped from rest and falls freely (ignoring air resistance). What happens to its velocity and acceleration as it falls?
Its downward velocity increases, while its downward acceleration remains constant at 9.81 m/s².