Physics 3 Flashcards
What is the main idea of Newton’s 1st Law of Motion?
Objects in Motion stay in motion, an object at rest stay at rest
Give 3 examples of Newton’s 1st Law in Action
Ball rolling down a hill, Throwing a ball in a moving car, trying to pull something heavy
What term best illustrates this law?
Inertia
Name 4 men who contributed to this idea
Aristotle, Galileo, Copernicus, Newton
What term is the best measure of inertia?
Mass
What units are the standard for mass?
Kg
What is the difference between mass and weight?
Weight is the force of gravity upon an object and Mass is how many molecules (how much stuff) is in an object.
Convert 72 kilograms to weight in pounds (1 kg= 2.2 lbs).
158.4lbs
What is the formula for converting mass into weight?
W = m x g
Convert 50 kg into weight
490N
What is the standard unit for weight in Physics?
N
What term describes when net force on an object equals zero?
Equilibrium
What happens to the force or tension on ropes when 2 ropes hold the weight
50% of the weight is placed in each
What happens to an object that falls from a tree?
The tree falls from it and gravity pulls it to the ground, when hitting the ground, the ground hits it back.
How does the earths spin affect something falling from a tree?
It will continue to spin with the earth even while falling
What happens to a ball tossed in the air vertically?
It will fall back at their feet
What happens to that ball when the person is in a car?
It will still fall at their feet as long as they maintain a constant speed
If forces of 15 and 25 N act on an object in opposite directions, what is the result?
It will move in the direction of the 25N push but only with 15N of force
If forces of 20 and 30 N act on an object in the same direction, what is the result?
50N of force in the same direction
How much mass is in an object that weights 30 N?
3.06Kg
What is the main formula that explains Newton’s 2nd Law of Motion?
F= mass x acceleration
What is the relationship between mass and acceleration?
Inversely proportional
What is the relationship between force and acceleration?
Directly proportional
What term describes the force that acts opposite any object in motion?
Friction
What is the equation for pressure?
Pressure = Force / Acceleration
What units are used for pressure?
Pascals (Pa)
27How much pressure is found when 15 N of force acts on 3 square meters?
P=15/3 P=5Pa
How much pressure is found when 15N acts on 10 square meters?
P=15/10 P=1.5Pa
When a cannon ball falls to the earth…what objects move?
The earth, the canon, the ball
What is the acceleration of the cannonball as it falls?
The same as when it was launched
If the cannonball weighs 5 kg, how much force is found when it falls?
F=ma F=5(9.8) F=49
How can a skydiver increase his/her acceleration?
If he stretches his legs/arms out he will slowdown and if he brings everything in to the center (like a pencil) then he will speed up)
If a racquetball full of quarters was dropped from a 3 story building, and a regular tennis ball was dropped at the same time, which would hit the earth first? Why?
They would hit at the same time because the heavier ball didn’t have time to accelerate faster than the normal one.
If a barbell with a mass of 12 kg was pushed with a force of 50 N, how fast would it accelerate?
f=ma 50N=12a a=4.16 m/s
If a car with a mass of 2200 kg was accelerating at 8 m/s2, how much force is produced?
f=ma f=2200x8 f=17,600
What term best describes a force?
Push, Pull, or Interaction
Interaction
What phrase best describes Newton’s 3rd Law of Motion?
To every action there is an opposite and equal reaction
If a dog is happy and wagging his tail (action), what is the reaction?
The tail wags the dog
When a kicker strikes a soccer ball with 15 N, how hard does the soccer ball strike back?
15N
When a person runs to the end of a dock and pushes down with both legs, why does the person leave the dock and fall in to the lake?
Because the dock pushes back
When a balloon filled with air (not tied) is released, why does it accelerate away?
Because the air comes out and pushes on the balloon
When a man kicks a soccer ball with 25 N of force, and another man kicks the same ball in the opposite direction with 25 N of force, what result will occur?
No movement
What words best describe the interaction of friction with an object?
Force in the opposite direction
When a mass of 15 kg falls to earth, at what force of air resistance will it reach its terminal velocity?
ar=w 15(N?)
