Newton's Laws
What is Newton's FIRST NAME?
Isaac
What is gravitational force?
An attractive (pulling) force between any 2 objects with mass
A boy is pulling a wagon to the right with a force of 6 N. At the same time, another boy is pulling the wagon to the left with a force of 15N.
What is the net force on the wagon?
9 N to the left
What is a force?
A push or pull on an object
What is the difference between mass and weight?
Mass is how much stuff an object has. Weight is mass times the acceleration of gravity
An object can only move when acted upon with a net external force.
TRUE OR FALSE
FALSE
What is normal force?
A force that opposes gravity. Acts perpendicular to an object that is lying on a surface
What is the acceleration of the 3 kg box that has 25 N of force applied to the right and 55 N left?
10 m/s/s to the left!
What is a contact force?
A force that acts when two objects are TOUCHING
If a person is moving to the right, then the forces acting upon it are NOT balanced.
TRUE OR FALSE
FALSE
Objects can move even if forces are balanced!
Unbalanced forces cause acceleration!
What is Newton's First Law?
The Law of Inertia!
An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by a net external force.
What is tensional force?
A pulling force! Typically through a rope, cable, string, etc.
Tommy has a mass of 100 kg on the earth. What is Tommy's mass on the moon where the force of gravity is approximately 1/6-th that of Earth's?
100 kg!
What is field force?
A force that acts at a DISTANCE
A golf pro places a ball at rest on the tee, lines up his shot, draws back his club, and lets one rip. During the contact of the golf club with the golf ball, the force of the club on the ball is ____ the force of the ball on the club and the acceleration of the club is ____ than the acceleration of the ball.
equal to, less than
What is Newton's Second Law?
Acceleration is directly proportional to the net force acting on an object and inversely proportional to the mass of an object.
Force is equal to mass times acceleration
What is friction?
Draw a free body diagram of a book that is sliding across a horizontal surface. The book is increasing speed!
Include friction, but neglect air resistance
What is inertia?
The tendency of an object to NOT accelerate/change speed
A rock is thrown straight up. What is the net external force acting on the rock when it is at the top of its trajectory?
The rock's weight! (gravity)
What is Newton's Third Law?
For every action there is an equal and opposite reaction!
What is air resistance?
A force that directly opposes motion of an object that is moving through the air
During a test crash, an air bag inflates to stop a dummy’s forward motion. The dummy’s mass is 75 kg. If the net force on the dummy is 825 N toward the rear of the car, what is the dummy’s deceleration?
What is equilibrium?
the state in which the net force on an object is ZERO
Why does an ordinary rifle recoil (kick backward) when fired? The barrel of a recoilless rifle is open at both ends. Describe how Newton’s third law applies when one is fired.
The force pushing the bullet has an equal and opposite force that pushes the gun back!