Vocabulary
Net Force
Newton's Laws
Word Problems
Mass, Weight &Gravity
100
What is the force that always opposes motion?
Friction (when 2 objects slide past each other)
100
When NET FORCE is zero, what is this called?
Equilibrium
100
Explain Newton's 1st Law of Motion.
Newton's 1st Law of Motion states: An object in motion or rest will continue in motion/rest at the same speed and in the same direction unless acted on by an unbalanced force.
100
What is the force needed to make a 3 kg ball move at an acceleration of 12 m/s/s?
Mass = 3kg Acceleration = 12 m/s/s Force = ? Answer: F= ma F= (3 kg)(12 m/s/s) = 36N
100
Define mass.
Mass is the amount of matter in an object. Mass can be calculated by the equation F/a
200
Define INERTIA
The relectance of an object to change its state of motion.
200
Describe the motion of an object with NET FORCE = 0.
Object is not moving.
200
Explain Newton's 2nd Law using the words force, mass and acceleration.
Newton's 2nd Law states that: Force = mass times acceleration or Acceleration = force/mass This means that in order to accelerate an object, you must apply a greater force or decrease the mass.
200
What is the mass of an object that is pulled with a force of 80 N at an acceleration of 5 m/s/s?
Force = 80 N Acceleration = 5 m/s/s Mass = ? M = F/a M = 80 N/5 m/s/s = 16 kg
200
Calculate your weight on Jupiter if your mass is 20 kg and the gravity on Jupiter is half as much as on Earth.
Force weight = mass x gravity Weight = (20 kg) x (4.9 m/s/s) Weight = 98 N *Know that the acceleration due to gravity on Earth is 9.8 m/s/s
300
Define MOMENTUM, and include the equation.
Momentum depends on mass and velocity. P = mv
300
What is the definition of NET FORCE?
The combination of all forces acting on an object.
300
Define Newton's 3rd Law and include an example using the words action and reaction.
Newton's 3rd Law states that for every action, there is a reaction that is equal in force, but opposite in direction. Examples could include: rocket ship, swimming, row boat, skateboard, etc.
300
Calculate the momentum of a 60 kg motorcycle traveling at a velocity of 20 m/s.
Momentum (p) = mass x velocity p = (60 kg) (20 m/s) = 1,200 kg/m/sec
300
Calculate your weight on Earth if your mass is 20 kg.
Force Weight = Mass x Gravity Weight = (20 kg) x (9.8 m/s/s) Weight = 196 N *know that the acceleration due to gravity on Earth is 9.8 m/s/s
400
Explain which has more inertia, a small car or a large truck?
A large truck has more inertia becasue it has more mass. Objects with more mass have more inertia becasue those obejcts resist moving.
400
How do you find NET FORCE of 2 forces acting in the same direction?
Add the forces up.
400
Explain which one of Newton's Laws is used in the example. Define the Law as well. You are riding in a car without a seatbelt. The car stops quickly. What happens to your body?
Your body continues forward and towards the windshield. This is Newton's 1st Law. Your body was in motion and wanted to stay in motion even when the car stopped short.
400
What is the momentum of an object at rest that has a mass of 8 kg.
momentum (p) = mass x velocity p = (8 kg) (0 m/s) = 0 Remember, if an object is not moving, it does not have any momentum!
400
Compared to your weight and mass on the Earth, if you went to the moon, your weight and mass would:
Mass would stay the same, but weight would decrease becasue gravity is less.
500
Define the Law of Conservation of Momentum.
The Law of Conservation of Momentum states that momentum is not lost or wasted, but rather transferred from one object to another.
500
Two people are pushing on opposite sides of a large box. The person on the left pushes with 30 N. The person on the right pushes with 34 N. What is the NET FORCE, and if the box moves, in which direction?
Opposite sides = subtract the forces. 34 N - 30 N = 4 N. Since this is an unbalanced force, the object will move. The object moves to the LEFT.
500
Explain why it is more difficult to push a wagon with more objects in it, versus a wagon that is empty. Which one of Newton's Laws is this?
When a wagon has more objects in it, it has more mass. In order to make an object with more mass accelerate, you must apply more force (push or pull) to the object. This is Newton's 2nd Law.
500
Using a diagram and arrows, show an object that is being pulled to the left with a force of 8 N and also being pulled to the right with 6 N. Is the object in motion?
Arrow to the LEFT with 8 N. Arrow to the RIGHT with 6 N. Net Force: subtract 8 N - 6 N = 2 N The object does move, it moves towards the left.
500
Explain Newton's Law of Universal Gravitation. Hint: Gravity depends on _________ and __________ .
Gravity depends on mass and distance. Gravity is greater between objects with greater mass rather than small mass. Gravity is greater between objects that are closer together rather than farther apart.
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