Kinetic Energy
which has more kinetic energy, a large dog sitting on a sidewalk or a small cat running down the street?
What is the small cat running down the street
what type of potential energy does an object like silly putty or a rubber band have
What is elastic potential energy
green plants convert light energy from the sun into _________ energy
What is chemical
There is a bell at the top of a tower that is 45 m high. The bell weighs 190N. Calculate the energy of the bell.
What is 8550 J potential energy
A student runs around the track at a constant speed. Specify what happens to K.E., P.E., and T.M.E. during this process.
K.E. does not change
P.E. does not change
T.M.E. does not change
which of the following is not used to calculate kinetic energy: mass, weight, velocity, height.
Height, Weight (we use mass, not weight!)
two copies of the same book are in a book case. one book is twice as high as the other. What's the difference between the two books, besides their height?
The higher book has twice the potential energy of the lower book.
Friction when rubbing your hands together causes some mechanical energy to change to ___________ energy
What is thermal (heat)
If a volleyball that weighs 5kg is served from a height of 3 m, it will travel at a speed of 10 m/s. Calculate the kinetic energy of the ball. Assume g=9.8m/s2
What is 250 J
A student slides down a steep street in a sled, with a slight increase in speed as they travel. Specify what happens to K.E., P.E., and T.M.E. during this process.
K.E. increases
P.E. decreases
T.M.E. decreases (due to friction converting some K.E. into thermal energy)
the greater ______ a constant-moving object has, the more kinetic energy it has
What is mass
which of the following is not used to calculate potential energy: mass, velocity, height?
What is velocity
when a plant falls from a window, its ________ energy is transformed into kinetic energy
What is gravitational potential
If a volleyball that weighs 5kg is served from a height of 3 m, it will travel at a speed of 10 m/s. Calculate the potential energy of the ball.
What is 147J
600 POINT QUESTION!
A 1kg ball is dropped in a vacuum, and reaches a velocity of 10m/s. How much does the ball's Total Mechanical Energy decrease during the fall?
ZERO! None is lost!
Two objects are traveling at the same speed. Object 1 has twice the mass of object 2. How do their levels of K.E. compare, specifically?
Object 1 has twice as much K.E.
a book and a feather are sitting on the same shelf. Which has more potential energy - why? Which has more kinetic energy - why?
Book has more PE because it has more mass. They have equal KE because they're both not moving.
When you put batteries in a flashlight and turn it on, the chemical energy changes to __________ energy.
Light (also correct: electrical, thermal)
a boulder that weighs 100 kg is raised 10 m above the ground and then dropped. Calculate the kinetic energy of the boulder at the bottom of the fall.
What is 9800 J
800 POINT QUESTION!
Object A is raised to 10m and identical Object B is raised to 20m. Which object will have the most kinetic energy when dropped to the floor? HOW do you know? Assume that no energy is converted to thermal energy.
Object B. There are a few ways to know. It is important to note that Object A and Object B are identical, which means they have the same mass!
-Object B is raised higher, which means that it has more potential energy because of its higher position. This means that when it reaches the floor (h=0m), ALL of that P.E. will have converted to K.E.
-Since Object B is raised higher, it will have more time to accelerate, and will therefore have a higher velocity (v) at the floor than Object A. More velocity means more K.E.!
An object with a mass of 10kg increases speed by 3 times. How does this affect the object's KE?
KE increases by 9 times.
the gravitational potential energy of an object depends on ________ and ________
What is mass and height
A baseball being hit by a bat is _____________ energy being converted into ____________ energy.
There are several different types of energy transfer happening!
Potential --> Kinetic
Kinetic --> Potential
Kinetic --> Thermal
Kinetic --> Sound
a baby carriage is sitting at the top of a hill that is 21 m high. the carriage with the baby has a mass of 1400 grams. Calculate the potential energy of the carriage and baby.
What is 288.12 J
1000 POINT QUESTION!
A rocket has a mass of 1,000kg and a velocity of 100m/s. To increase it's K.E. to 45,000,000J (that's 45 million Joules, or 45 megajoules), what are TWO possible changes that you could make to the rocket? Assume that you would only make one of the changes, but please specify what both changes could be! Specify actual number values to change, NOT just what you would multiply stuff by!
1) The rocket currently has 0.5 x 1,000kg x (100m/s)2 = 5,000,000J of K.E.
2) To increase the K.E. of the rocket by 9 times, you would either:
a) triple the velocity to 300m/s
b) increase the mass of the rocket 9 times to 9,000kg.