Types of Forces
Type of force when there is no change in motion.
Balanced force
The _______ of the vector represents the strength of the force.
magnitude
A bowling ball hits the bowling pins at the end of the lane and knocks them all over earning a strike! What was the action force and reaction force?
Action force: Bowling ball hitting pins
Reaction force: Bowling pins hitting the bowling ball
A push or pull on an object.
Force
Danny stands next to a wall on a frictionless skateboard and pushes the wall with a force of 40 N. How hard does the wall push on Danny?
40 N
Type of force that is also called drag.
air resistance
Frictional force
Calculate the acceleration of a car if the force on the car is 450 Newtons and the mass is 1300 kilograms.
0.35 m/s/s
This type of force causes acceleration.
Unbalanced force.
You and Danny ride in his fancy space shuttle to the moon. You both are getting out of the shuttle at the same time and fall to the ground. Do you land at the same time?
Yes because there would not be air resistance on the moon causing both you and Danny to accelerate at the same rate.
Type of force that depends on the mass of objects and the distance between objects.
gravitational force
Which force is always perpendicular to the surface of a stable object?
Normal force
On the surface of Earth, how much does a 10 kg mass weigh? Hint: Acceleration due to gravity on Earth is 9.8 m/s/s.
98 N
An object's tendency to resist motion is called _________ and can be increased by adding mass.
Inertia
You've decided that you want your first job to be Danny's chauffeur. Unfortunately, you've never had a job before so you show up late on the first day. You decide the best course of action is to drive Danny 100 mph all the way to his gig. As you turn the corners Danny's body is thrown into the side of the car resulting in a black eye. You immediately get fired. Which of Newton's Laws would describe why Danny's body was thrown around in the car?
Newton's first law
In which of the following examples, there is zero net force acting on the object? A car drives around a circular path at a constant speed. A person pushes on a door to hold it shut. A ball, rolling across a field, slowly comes to a stop.
A car drives around a circular path at a constant speed.
A 1-kg rock is thrown at 10 m/s straight upward. Neglecting air resistance, what is the net force that acts on it when it is halfway to the top of its path?
In the absence of air resistance, the only force exerted on the 1-kg rock is simply the force gravity, mg. That’s 9.8 N downward, at any speed and anywhere along its trajectory.
Two cars accelerate at 2 m/sec2 . Car A has a mass of 750 kg, while Car B has a mass of 1000 kg. What forces are required to accelerate each car?
Car A: 1500 N
Car B: 2,000 N
The sum of forces is called ______.
Net force
Danny decides to take you to Worlds Of Fun. One of the rides requires partners to take turns pushing each other to gain speed. Danny gets in the first car and you start pushing. You find that he is very hard to move. After Danny's turn, you get in the car and Danny seems to have no trouble moving it. Which of Newton's Laws explains this?
Newton's 2nd Law
This type of force can be horizontal or vertical and can be increased by adding mass.
Normal force
A student is pushing a 50 kg cart, with a force of 600 N. Another student measures the speed of the cart, and finds that the cart is only accelerating at 3 m/s2. How much friction must be acting on the cart?
450 N
The force exerted against the recoiling cannon is just as great as the force that drives the cannonball inside the barrel(Newton’s 3rd Law). Using Newton’s 2nd Law, explain why the cannonball accelerates more than the cannon?
The change in velocity of the cannonball is so large compared with the change in velocity of the cannon. A given force exerted on a small mass produces a large acceleration, while the same force exerted on a large mass produces a small acceleration.
The difference between mass and weight.
Mass is the amount of stuff or matter in an object while weight is your body's acceleration towards Earth due to gravity.
Danny has decided to buy himself an old war cannon. While firing this cannon he notices that the cannon moves when fired. Which of Newton's Laws describes what is happening and which direction will the cannon move when fired?