Estefania Alvarez, Alessandra Gomez, Alejandra Cardona Flashcards
What is work?
a force applied through a displacement
How can work be calculated?
W=(F)(S)
A 52.0-kg skater moves at 2.5 m/s and stops over a distance of 24.0 m. Find the skater’s initial kinetic energy. How much of her kinetic energy is transformed into other forms of energy by friction as she stops? How much work must she do to speed up to 2.5 m/s again?
1/2 mv^2
=1/2(52.0Kg)(2.5 m/s)^2 =160J
Speed Up
= 1/2(52.0Kg)(2.5 m/s)^2 - 1/2(52.0 kg)(0.00m/s)^2=+160J
An 875.0-kg car speeds up from 22.0 m/s to 44.0 m/s. What are the initial and final kinetic energies of the car?
=1/2 mv^2
Initial Ki
Ki= 1/2(875.0kg)(22.0)^2 =2.12x10^5 J
Final Ki
1/2(875.0kg)(44.0)^2 =8.47 10^5J
What is gravity? .
A force that attracts all objects toward each other
What is inertia .
The tendency of an object to resist a change in motion
Newton first law of motion .
an object at rest will stay at rest and an object in motion will stay in motion
What is the ‘g’ value? .
g=GM/R^2
What is Energy?
Science Usage
the ability of a system to produce a change in itself or the world around it
Common Usage
the capacity of acting or being active
A students walks 100 m in 70 sec. What is the students speed? .
s=1.4m/s
What does the gravitational depend on? e
the mass of each object and the distance between the centers of the two objects.
What is the Mechanical Energy of System equation?
ME=KE+PE
what is the law of universal graviton? e
all objects in the universe attracts other object
Gravitational potentional energy formula, measured in Joules (J)? .
Eg
what two factors determine the strength of the force of gravity between two objects? e
Mass and Distance
Conservation of Mechanical Energy in roller coasters.
The roller-coaster car is nearly at rest at the top of the first hill, and the total mechanical energy in the Earth-roller coaster car system is the system’s gravitational potential energy at that point. If a hill farther along the track were higher than the first one, the roller-coaster car would not be able to climb the higher hill because the energy required to do so would be greater than the total mechanical energy of the system.
A car has a mass of 2000 kg and is traveling at 28 meters/second. What is the cars KE, in joules? .
784,000
if mass increases
and distance stays the same
the force of gravity? e
increases
Conservation of Mechanical Energy in skiing.
When you ski down a steep slope, you begin from rest at the top of the slope and the total mechanical energy is equal to the gravitational potential energy. Once you start skiing downhill, the gravitational potential energy is transformed to kinetic energy. As you ski down the slope, your speed increases as more potential energy is transformed to kinetic energy.
two sentences about the relationship among mass, distance, and the force of gravity between two objects? e
if mass stays the same and the distance decreases the force of gravity between two objects increases
what two factors keep the plants in orbit? e
inertia and gravity
what statement is true about the moons orbit around the sun? e
earths gravity pulls the moon towards it and inertia keeps the moon moving ahead
how does newtons first law of universal graviton apply to earth and the moon? e
earth pulls on the moon and every object attracts another object
what is mass? e
Amount of matter in an object
true or false: forces on earth are different from those elsewhere in the universe e
false
A car has a mass of 2000 kg and is traveling at 28 meters/second. What is the cars KE, in joules? .
784,000
Work formula? .
W=F X d
What is gravitational potential energy of 1 kg book that is 1 meter above the ground? g=9.8 m/s
9.8 J
Equation of mechanical advantage
MA= Fr/Fe
A bike rider approaches a hill at a speed of 8.5 m/s. The combined mass of the bike and the rider is 85.0 kg. Choose a suitable system. Find the initial kinetic energy of the system. The rider coasts up the hill. Assuming friction is negligible, at what height will the bike come to rest?
=29.7m/s
=√(2)(9.80 m/s^2)(45.0m-40.0m)
9.90m/s
They do not compact
