Nature of Forces + Momentum
Define force.
a push or a pull between objects that can cause a change in motion.
If an object is moving to the right, what is the direction of the frictional force on that object?
to the left
What is the acceleration due to gravity?
If two objects are pushed with the same force but one object has more mass than the other, how will their accelerations compare according to Newton’s Second Law? If you increase the force on object, what happens to the objects acceleration?
The greater mass will have less acceleration, the smaller mass will accelerate faster.
If you increase the force, acceleration increases.
What would increase friction more: putting more or less pressure on an object to move it?
more
What happens if the Net Force on an object is NOT zero?
It will move
Which type of friction is required to overcome in order for an object to go from being still to moving.
static friction
If a feather and bowling ball are dropped on the Moon at the same time, which hits the ground first?
Trick question - they hit at the same time because there is no outside force other than gravity so they accelerate at the same rate.
State Newtons 3 Laws of Motion
1. an object at rest will stay at rest unless an outside force acts upon it
2. F = ma
3. For every action there is an action of equal magnitude in the opposite direction
What two variables impact momentum directly?
Mass and velocity
What is a newton?
the force required to move 1 kg of an object accelerating at 1 m/s/s.
If you placed two heavy objects on a piece of glass, would you need more of less force to move it compared to if they were placed on sand paper?
less force
Which two factors have the biggest impact on two objects gravitational force?
distance to one another and mass.
A soccer ball is sitting still on the field. What must happen for the ball to start moving, and which of Newton’s laws explains this?
An outside force must act on it. This is Law 1.
What happens to an objects motion if it goes from experiencing centripetal force to NOT experiencing that force?
It will begin to move in a straight path instead of a circular path.
If a 10N force to the right is applied to an object while a 4N force to the left is applied, what is the net force?
6N to the right
Provide an example of centripetal force in action.
Answers will vary - earth orbiting sun, a tether ball around a pole, a person doing shot put, a merry-go-round or gravitron, a centrifuge mixing chemicals.
If a dog weighs 30N on Earth, what is it's weight on the Moon?
5N
When a swimmer pushes off the wall of a swimming pool, they move forward through the water. Using Newton’s Third Law, explain what force the swimmer applies and what equal and opposite force causes them to move forward.
The swimmer pushes the wall with their feet (the action) and the wall pushes the swimmer forward (the equal action in the opposite direction)
The mass of a green car is 100 kg and the mass of a blue car is 100 kg. The green car travels at 5 m/s, while the blue car is not moving. If the green car hits the blue car, pushing it forward, what is the total momentum after the collision?
500 kgm/s
State the law of conservation of momentum.
In the absence of an outside force, momentum of two interacting objects does not change before and after the interaction.
What direction is centripetal force?
If v = at, and an object free falls for 3 seconds, what will its end speed be?
29.4 m/s
What is inertia and how does it relate to Newtons Laws?
inertia is the resistance to change in motion, and it relates to Newtons 1st law bc it describes how an object has a natural tendancy to continue doing what it's doing (stay at rest or continue moving)
Is the gravitational force stronger on an apple in a bowl on the table or an apple in a tree? Why?
The table . It's decreased height in comparison to the tree, making it closer to center of Earth would increase the gravitational force slightly. (would you be able to feel the difference, no. would you be able to calculate the difference, yes)