Chapter 4, Lesson 1: gravity
What are the units of weight
Newton's and pounds
How did Einstein's and Newton's theories differ in terms of explaining the cause of gravity?
Newton's theory identified mass as the factor that causes gravity. On the other hand, Einstein's theory identified the curvature of space-time as the factor that causes gravity.
What does earth's gravity affect?
Our daily lives, motion, and nearby objects with smaller mass such as the moon
What does earth's gravity pull on?
Stationary and moving objects
What does Newton's law of universal gravitation describe?
Strength of gravitational force
What observation about light supported Einstein's theory
The Sun bent the light from a star. This bending made the star appear in a slightly different position from its actual position. This observation supported Einstein's theory.
What observation about light supported Einstein's theory?
The Sun bent the light from a star. This bending made the star appear in a slightly different position from its actual position. This observation supported Einstein's theory.
what is common in all projectiles?
a constant rate of acceleration for ANY projectile
What is the constant rate of acceleration in a projectile known as?
acceleration due to gravity
Two metal balls are dropped from the top of a two-story building at the same time. One ball is twice as heavy as the other ball. Which statements about their motion are true? Assume that air resistance isn't a factor.
constant acceleration in both, land at same time
What is Newton's law of universal gravitation?
explanation of relationships between mass, distance,and force of attraction. how to calculate strength of force of gravity between two objects
What theory was made to help Newton's their in the places it lacked? How and by who?
general relativity theory It says that a concept called spacetime causes gravity. Massive objects such as Earth bend the spacetime. This bending acts like a force German scientist Albert Einstein
What do newton'S laws of motion explain?
how force and motion are related when objects interact with Earth.
Lincoln weighs 400 newtons. What's his mass rounded to the nearest kilogram? Assume that acceleration due to gravity is 9.8 N/kg.
m = 400 N ÷ 9.8 N/kg 40.8 kg.
What doesn't acceleration due to gravity NOT depend on?
mass
What does the force of gravity between two objects depend on?
mass and distance (higher mass and closer = stronger gravitational force)
What are the only observational forces of gravity applied ONTO earth
moon and sun sun keep earth in orbit moon causes ocean tides
What does air resistance affect?
small mass + large surface area
What does the density of the lines In a force diagram represent?
strength of a force of gravity. (More dense = more force)
What did Newton discover about the motion of projectiles and gravity
the force of gravity depends on the amount of mass. The greater the mass, the stronger the attraction between two objects.
What is weight?
the force of gravity on an object
When Earth pulls on an object, that object also pulls on Earth. The values of these two forces are ——- This phenomenon can be explained using Newton's ——— We see the object move but not Earth because there's a difference in their ——-
the same Third law mass
What happens if a heavier object and a lighter object are dropped from the SAME height?
they will reach the ground at the same height.
according to Newton's ——— law,
third, every obj3ct also pulls on earth
What equation relates weight, mass and acel.. due to gravity
weight (W) = mass (M) times acceleration due to gravity (g)
When is gravity constant?
when air resistance isn't a factor
When does gravitational force increase?
when mass increases
What was the motion of the fireball? What caused a change in velocity? How are our observations unreliable? How does earth attract or pull on objects?
1. fireball moves upward, then falls 2. fireball slows when moving up speeds when moving down, changing velocity. 3. Gravity caused a change. 4.fireball seemed to speed upward, measurements show it slowed. 5.measurements show earth attracted fireball entire flight.
Kenna has a mass of 30 kilograms. What's her weight in newtons? Assume that acceleration due to gravity is 9.8 N/kg.
30 x 9.8 = 294
What does one pound equal in Newtons?
4.45
What is the ratio of force to mass?
9.8 Newton's per kilogram
What is the constant rate of acceleration for a projectile?
9.8 m/s squared. Velocity increases every by 9.8 meters per second
What is gravity?
A force that pulls objects toward each other;
What is a projectile?
A moving object upon which the only acting force is gravity
What is a force field and how is it represented?
A reign of space where and object exerts a force on other objects.... Diagrams: direction of arrows = direction of force. Arrows show gravitational pull on smaller objects around it.
Explain why Einstein's general relativity theory is important to the makers of GPS systems.
According to Einstein's theory, gravity affects time. GPS systems measure the time a signal takes to travel from a satellite to Earth. So to be accurate, the systems have to adjust time using Einstein's theory.
Who tested the speed difference in different weighted objects from falling at the same height? How?
Galileo Galilei dropped 2 spheres of different masses from the top of the leaning tower of Pisa.
What does earth exert?
Gravitational force far out into space. We call this area a force field
How does newton'S second law apply to gravity
If air resistance is ignored, acceleration of a falling object is equal to the ratio of force of gravity to mass (9.8)
Which statements are explained by Newton's law of universal gravitation?
The strength of Earth's gravity decreases as an object gets farther from Earth. The strength of gravity depends on an object's mass.
What was a result to Galileo's test? What did he determine?
The two objects sped up at the same rate of acceleration and landed at the same time. He determined that acceleration due to gravity is independent of an object's mass.
Difference between mass and weight
Weight is affected by gravity, but mass isn't.