Net Force
What is net force?
The total combined forces acting on an object.
What is force?
A push or pull on an object.
Newton's First Law is the Law of ______ .
Motion.
Is constant speed a balanced or unbalanced force?
Balanced Force
Describe how to calculate net force.
Arrows facing same direction = add
Arrows facing opposite direction = subtract
Calculate your total.
What is motion?
Movement or change in direction.
A book rests on a table.
According to Newton's 1st Law of Motion, if the force of gravity is pulling the book down, what keeps the book from crashing to the floor?
A) The floor pushes back up on the book creating balanced forces.
B) Inertia of the book holds it up.
C) The table presses back up on the book creating balanced forces.
D) The table presses back up on the book with a greater force creating unbalanced forces.
C) The table presses back up on the book creating balanced forces.
There are two scenarios below.
1. A chromebook laptop sliding on a desk at constant speed.
2. An airplane landing on a runway.
Which force is balanced and which force is unbalanced?
Balanced - A chromebook laptop sliding on a desk at constant speed.
Unbalanced - An airplane landing on a runway.
1. 55 N --------> [ 25Kg ] 13 N -------->
2. 20 N --------> [ 25Kg ] 20 N -------->
3. 20 N --------> [ 25Kg ] <--------20 N
4. 10 N ------> [ 25kg ] <-------- 10 N
5. <-------- 350 N [ 25Kg ] 350 N -------->
Which numbers do NOT describe a change in motion?
A) 1, 3
B) 1, 4, 5
C) 3, 4, 5
D) 3, 4
C) 3, 4, 5
What is a Newton?
The unit used to measure force.
A box experiences two forces.
On the left, the box is being pulled 95 Newtons. On the right, the box is being pulled 130 Newtons.
Which statement best describes the motion of the cube?
A) The object will move to the left because the forces are unbalanced.
B) The object will remain at rest because the forces are balanced.
C) The object will move to the right because forces are unbalanced.
D) The object will move to the right because the forces are balanced.
C) The object will move to the right because forces are unbalanced.
Which of the following is an example of balanced forces?
A) A plant rests on a window.
B) A track sprinter begins to run from the starting point.
C) A Nascar slows down on the race track.
D) A truck accelerates down hill.
A) A plant rests on a window.
Two forces are applied to a 15 kg box. The box is a rough surface.
55 N --------> [ 15Kg ] <----13 N
Which statement best describes the net force of the box?
A) The net force is 68 N to the right
B) The net force is 42 N to the left
C) The net force is 13 N to the left
D) The net force is 42 N to the right
D) The net force is 42 N to the right
What is an unbalanced force?
Net force greater than zero; change in motion/direction
According to Newton's Law of Motion, which of the following objects will change its motion?
A) A wagon pulling another wagon with the same amount of force.
B) A stool resting on the floor with balanced forces acting in opposite directions.
C) A tennis ball rolling on the field with friction acting in the opposite direction.
D) A two-wheeler on a smooth leveled road, going at a constant rate.
C) A tennis ball rolling on the field with friction acting in the opposite direction.
The following list includes six situations.
1. A pencil sliding across a table a constant speed
2. A basketball rolling down a hill
3. A motorcycle driving a constant speed of 25 m/s
4. A person swinging back and forth
5. A box sitting on a shelf
6. A hummingbird landing on a tree
Which objects on the list experience balanced forces?
A) The motorcycle, box, and the hummingbird
B) The box, the pencil, basketball, hummingbird
C) The pencil, box, and the motorcycle
D) The hummingbird, the person, the basketball
C) The pencil, box, and the motorcycle
Two forces are applied to a 100 kg box. The box is a rough surface.
150 N --------> [ 100 kg ] <---- 178 N
Which statement best describes the net force of the box?
A) The net force is 328 N to the right
B) The net force is 28 N to the left
C) The net force is zero
D) The net force is 28 N to the right
B) The net force is 28 N to the left
What is a balanced force?
Zero net force; constant speed; at rest
A large yacht and a small fishing boat were in a body of water near each other. Both the large yacht and the fishing boat were initially moving at the same steady speed.
Please select ONE correct answer in each box to complete the sentence.
If the large yacht and the fishing boat stopped their ignitions at the same time, the fishing boat would take _____ to halt than the yacht, because the fishing boat has _____ inertia.
A) shorter time; less
B) longer time; less
C) same amount of time; more
D) longer time; same amount
A) shorter time; less
A truck driver is driving down a street at 50 mph. The truck driver suddenly slams his brakes and makes the truck come to a stop quickly.
According to Newton's First Law, what would be the resulting motion of a passenger if they did not have a seatbelt on.
A) The passenger would be pushed back against the seat.
B) The passenger would be pushed against the door from an outside force.
C) The passenger would stop with the truck at the same time as the truck.
D) The passenger would continue to move forward.
D) The passenger would continue to move forward.