Haroldo Morales, Jose Urrutia, Vanya Sanchez - Gravitational Motion, Rotational Motion, Work, Energy

Question 1

Remember - What is Gravitational Motion?

Answer 1

The gravitational force exerted by bodies on one another as a function of their mass

Question 2

Identify - What does the F represents on W=Fd?

Answer 2

F = Force

Question 2

remember - what is the SI unit for work?

Answer 2

joule (J)

Question 3

remember - What is energy?

Answer 3

energy is the ability of a system to produce a change in itself or the world around it.

Question 4

calculations question - 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? How much work is done on the car to increase its speed?

Answer 4

initial - 2.12 x 10^5 J
final - 8.47 x 10^5 j
work - 6.35 x 10^5 J

Question 5

Identify - What is the formula for Potential Energy?

Answer 5

PE = mgh

Question 6

Think - Can energy be lost?

Answer 6

Yes, when energy is transformed from one form to another is energy loss.

Question 7

Identify - Which is a rate at which energy is transformed?

Answer 7

Power

Question 8

Identify - What is the ability of an object to produce a change in itself or the world around it?

Answer 8

Energy

Question 9

Think - When is work done on a system?

Answer 9

When a force is applied through a displacement

Question 10

remember - How do you find the average angular velocity of an object

Answer 10

The angular velocity equals the angular displacement divided by the time required to make the rotation.

Question 11

remember - What did Kepler’s first law state?

Answer 11

Kepler’s first law states that the paths of the planets are ellipses, with the Sun at one focus.

Question 12

identify - Which of Keplers laws stated that an imaginary line from the Sun to a planet sweeps out equal areas in equal time intervals

Answer 12

Kepler’s second law

Question 13

Identify - Which of Kepler’s laws states that the square of the ratio of the periods of any two planets revolving about the Sun is equal to the cube of the ratio of their average distances from the Sun.

Answer 13

Kepler’s third law

Question 14

Solve - An electric motor lifts an elevator 9.00m in 15.0s by exerting an upward force of 1.20*104 N.
What power does the motor produce in kW?

Answer 14

W/t = P
= FD/t
(1.20 * 10)^4 (9.00m) / (15.0s)
= 7.20 kW

Question 15

identify - What is the formula used in Kepler’s third law?

Answer 15

The square of the ratio of the period of planet A to the period of planet B is equal to the cube of the ratio of the distance between the centers of planet A and the Sun to the distance between the centers of planet B and the Sun. (I couldn’t write the formula)

Question 16

Calculation question - Galileo measured the orbital radii of Jupiter’s moons using the diameter of Jupiter as a unit of measure. He found that Io, the closest moon to Jupiter, has a period of 1.8 days and is 4.2 units from the center of Jupiter. Callisto, the fourth moon from Jupiter, has a period of 16.7 days. Using the same units that Galileo used, predict Callisto’s distance from Jupiter.

Answer 16

answer - 19 units
the formula used: The square of the ratio of the period of planet A to the period of planet B is equal to the cube of the ratio of the distance between the centers of planet A and the Sun to the distance between the centers of planet B and the Sun. (couldn’t write the formula)

Question 17

Solve - The gravitational force between two spheres that are touching each other, each with a radius of
0.3 meter and a mass of 1,000 kilograms, is given by:

Answer 17

F = 6.67 * 10^-11 N-m^2 / kg^2
1000kg * 1000kg / (0.3m + 0.3m)^2
= 0.000185 N

Question 18

remember - What was newtons law of universal gravitation?

Answer 18

Newton’s law of universal gravitation states that objects attract other objects with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 19

identify - what was the formula for newtons law of universal gravitation?

Answer 19

Formula = The gravitational force is equal to the universal gravitational constant, times the mass of object 1, times the mass of object 2, divided by the distance between the centers of the objects, squared.

Question 20

Solve - For the force of gravity a person with a mass of 60 kg sitting 1.5 meters from another person with a mass of 45 kg

Answer 20

F = 6.673 * 10^-11
N-m^2/Kg^2 * 60kg * 45kg / 1,5m^2
= 8.0 * 10^-8 N

Question 21

Calculation question - Assume that a satellite orbits Earth 225 km above its surface. Given that the mass of Earth is 5.97 × 1024 kg and the radius of Earth is 6.38 × 106 m, what are the satellite’s orbital speed and period?

Answer 21

Answer - This is approximately 89 min, or 1.5 h.

PROCEDURE:

1. Determine the orbital radius by adding the height of the satellite’s orbit to Earth’s radius.
2. solve for speed
3. solve for period

Question 22

Solve - a. 22.0-kg tree limb is 13.3 m above the ground. During a tropical storm, it falls on a roof that is 6.0 m above the ground.

b. Find the kinetic energy of the limb when it reaches the roof. Assume that the air does not work on the tree limb

Answer 22

= 0.0 j * 1.6 * 10^3 j - 0.0 j

= 1.6 * 10^3 j

Question 23

Calculation question - A child sits on a carousel at a distance of 3.5 m from the center and rotates through an arc length of 6.5 m.
What is the angular displacement of the child?

Answer 23

1.9 rad

Question 24

Think - Work done by friction can be positive?

Answer 24

No, because work can never be positive. Friction, by its nature, always acts opposing the relative motion between two surfaces. work done by friction can be zero when there is no relative motion.

Question 25

Identify - What equation is used in order to find the Average Angular Velocity of an object?

Answer 25

The angular velocity = the angular displacement divided by the time required for the rotation.

Question 26

calculation - Find the gravitational force of attraction between a body of unit mass and the Moon.

Mass of the moon = 7.4 x 10^22 kg
radius of the moon = 1.74 x 10^6 m
G = 6.67 x 10^(-11) N-m^2/kg^2

Answer 26

answer: 1.63N

formula used = f= GMm / r^2

Question 27

calculation - What is the gravitational force between the Sun and the Earth?

(take, the mass of the Sun = 1.99 x 10^30 Kg.
mass of the Earth = 6 x 10^24 Kg
G = 6.67 x 10^(-11) N-m^2/kg^2
and distance between the Sun and the Earth=1.49 x 10^11 m)

Answer 27

answer: 3.587 x 10^22 N

formula used: f = GM M/ R^2

Question 28

calculation - Find the acceleration due to gravity on the surface of Jupiter using the data given below;

(Mass of Jupiter: M = 1.9 x 10^27 kg,
the radius of Jupiter = R = 7 x 10^7 m

Answer 28

answer: 25.86 ms^2

formula used: g= GM/r^2

Question 29

calculation - A hockey player uses a stick to apply a constant 4.50-N force forward to a 105-g puck sliding on ice over a displacement of 0.150 m forward. How much work does the stick do on the puck? Assume friction is negligible.

Answer 29

Answer: 0.675

steps: Identify the system and the force doing work on it.
Sketch the situation showing initial conditions.
Establish a coordinate system with +x to the right.
Draw a vector diagram.
Use the definition for work.