S4w6 Homework - balanced and unbalanced forces

Review questions: Energy of a rollercoaster at the top of the hill at the start of the ride is

heat energy is a form of

We've talked about a few things in physics so far. Do you remember what is and is not a vector?

Review vocabulary

These vectors have not been drawn head to tail already. redraw one and draw the resultant vector for each problem

Newtons second law is that force = mass x acceleration. If the object isn't moving, what is its velocity? (don't worry about units)

Newtons second law is that force = mass x acceleration. If the object isn't moving, what is its acceleration? (don't worry about units)

Newtons second law is that force = mass x acceleration. If the object isn't accelerating, what is the force on the object?

You put a book on a table, it is not moving. Is gravity still a force on the object?

what kind of force is the table putting on your book?

you magically change your book into a 1000kg boulder. Youre table is not that strong, its starts to crumble. Does the velocity of your boulder change?

As your table is crumbling under the weight of the massive boulder, what can you say about the force from the table to the boulder? how is it different from the force of the table on the book?

watch this video.

do you have any questions

in a tug of war game, if one team is pulling harder than the other, is the flag in the center moving or stationary?

in the above scenario, are the forces on the rope balanced or unbalanced?

if the teams are pulling with the exact same force in opposite directions, the flag will be

In this case the forces are

It bothers me that they put a satellite in orbit around the earth as an example of an object in motion staying in motion unless acted on by an unbalanced force. if an object in motion in space is not being acted on by an unbalanced force then it will

An object in orbit is moving

An object in orbit is being held in orbit by

If an object is moving at a constant velocity, what is its acceleration?

Something in orbit may be going at a constant speed, but is not going at a constant velocity. why?

What is a balanced force?

What is an unbalanced force?

One of the common misconceptions in physics is that the balanced forces that keeps an object stationary are the "equal and opposite reactions" described in Newton's third law. They are not. Whether a person is falling from a building or standing on the ground, the equal and opposite force of gravity of the earth pulling on them, is them pulling gravitationally on the earth. The equal and opposite force of the earth pushing up on the person standing on the ground is the person pushing down on the ground. Newton's 3rd law force pairs are always between the same two objects. Match the force pairs that are the equal and opposite reactions in newton's 3rd law.

8th graders! A lot of times when we are trying to work out how fast something should be moving, it is useful to create a force diagram. watch this video on force diagrams.

A horse accelerating a sled to the right. Diagram all forces acting on the sled. assume there is friction, but not a lot of friction

A bird egg is free-falling from a nest in a tree. Diagram the forces acting on the egg.

A hockey puck is gliding across the ice to the left and slowing down. Diagram the forces acting on the puck as it glides.

Come up with a simple scenario that was not in the above video that you could create a free-body diagram for in class.