P1 - 1.4 Gravitational Potential Energy + Gravity Flashcards
What is gravity
The force of attraction between 2 objects
What can affect a force of attraction between two forces in gravity
Mass
How far apart the objects are
Is gravity between 2 objects felt strongly or weak
Strongly
Is gravity between 2 far away objects felt strongly or weak
Weak
What is a gravitational field
Gravity having a big influence over nearby objects
What is gravity having a big influence over nearby objects called
Gravitational field
What is the strength or a gravitational field called
The gravitational field strength
What letter stands for gravitational field strength
g
Roughly what is earths gravitational field strength
9.8 Newtons/ Kg
Roughly what is the gravitational field strength of the moon
1.6 Newtons / Kg
Why is the moons gravitational field strength much smaller than earths
The moon is a lot smaller in size
What happens when an object enters a gravitational field
It experiences a force of attraction
What is the force of attraction known as in physics
The weight
How do we work out the weight of an object in gravitational potential energy
Mass x gravitational field strength = weight
Scenario:
If a person was to stand on earth with a weight it 60kg
Assuming that the gravitational field strength is 9.8 N
Mass x gravitational field strength = weight
60x9.8=588N
What is weight measured in
Newtons
What is the difference between weight and mass in physics
Mass is an intrinsic property
Weight is the force acting on it in a gravitational field
To lift up and object what is required
Energy or work
When we lift up an object what is transferred to the gravitational potential energy store
Energy
When we lift up an object where is energy transferred to
That objects gravitational potential energy store
What is the calculation to find gravitational potential energy (Ep)
Ep = mgh
Gravitational potential energy = mass x gravitational field strength x height
What is the unit for mass
Kg
What is the unit for gravitational field strength
N/Kg
Newtons per kilogram
What is the unit for height
Metres
What is the unit for gravitational potential energy
Joules (J)
If i were to drop an apple that has a mass of 100g from a height of 3 metres what would the gravitational potential energy be?
Ep=mgh
1) convert the units
100g —> kg = 100/1000= 0.1kg
2) put numbers into the calculation
0.1x9.8x3= 2.94J
What can we think of when we talk about weight in physics
The force acting on an object due to gravity
What can we think of when we refer to mass in physics
The amount of “stuff” we have
What is the weight of a 70 kg object on earth?
(The Earth’s gravitational field strength is 9.8 N/kg)
Weight = mg
W = 70x9.8
=686N
A car on earth experiences a downwards weight of 8820 N, what is the mass of the car?
(The Earth’s gravitational field strength is 9.8 N/kg)
W=mg
W = 8820N
G= 9.8N/kg
W/g = m
8820/9.8 = 900kg
Tony has a mass of 65 kg on Earth. What is Tony’s mass on the moon?
The mass of an object is the same as anywhere in the universe
65kg
True or False:
The mass of an object is the same anywhere in the universe.
True
Tony’s mass is 65 kg. What is his weight on Earth?
(The Earth’s gravitational field strength is 9.8 N/kg)
W = mg
W = 65x9.8
W = 637N
Tony’s mass is 65 kg. What is Tony’s weight on the moon?
(The moon’s gravitational field strength is 1.6 N/kg)
W = mg
W = 65 x 1.6
W = 104N
Tony, who has a mass of 65 kg, climbed the stairs from the ground floor, up to the fourth floor, which is 20 m higher. How much gravitational potential energy did Tony gain?
(The Earth’s gravitational field strength is 9.8 N/kg)
Ep = mgh
M= 65kg
H= 20m
G= 9.8
Ep= 65x9.8x20
Ep = 12740J
Freya, who has a mass of 60 kg, jumps from a boat into the sea. Just before she hits the water, she has lost 1,470 J of gravitational potential energy.
Ep = mgh
Ep = 1470
M = 60kg
G = 9.8
H = ?
Ep/mg = h
1470/60x9.8 = 2.5m
