Isabella Ponsa, Andrea Vallecillo, Enrique Luna Gravitational Motion, Rotational Motion, Work, Energy.

Question 1

What is the definition of energy? -Remember

Answer 1

Is the ability to cause change or work

Question 2

What is the definition of work?

Answer 2

A force that causes displacement or work on an object.

Question 3

What is the formula of work and what does the variables represent?

Answer 3

W=Fd or work=force * the magnitude of displacement.

Question 4

What is the formula of energy? -Remember

Answer 4

The energy stored in an object due to its position and height is known as potential energy and is given by the formula: P.E. = mgh

Question 5

What units are used to measure work?

Answer 5

Joules

Question 6

Can work be negative?

Answer 6

Yes, work can be both positive and negative. When you are in the same direction is positive, on the other hand, if displacement is in opposite direction is negative.

Question 7

A woman applies a force of 700N at a distance of 300cm.

Calculate the amount of work being done.

Answer 7

700*3=2100

Question 8

Two objects of masses 2 kg and 4 kg are moving with the same momentum of 20 kg m s-1. -Understand

a. Will they have same kinetic energy?
b. Will they have same speed?

Answer 8

a. No, the object of mass 2kg has a kinetic energy of 100J and the object of mass 4kg has an energy of 50J.

1 Procedure:
KE= p2/2m
=(20)2/2X2
=400/4 = 100J

2 Procedure:

(20) 2/ 2X4 = 400/8 = 50J
b. Therefore, they will not have the same speed. The object of mass 2kg is faster.

Question 9

Pushing a box through a ramp means?
a. Less work
b. More work
C. The same amount. of work, lifting up.

Answer 9

C. The same amount. of work, lifting up.

Question 10

State Kepler’s first law.

Answer 10

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

Question 11

State Kepler’s second law.

Answer 11

Kepler’s second law states that an imaginary line from the Sun to a planet sweeps out equal areas in equal time intervals.

Question 12

Identify the law that states that the square off the ratio of the periods of any two planets revolving around the Sun is equal to the cube of the ratio of their average distance from the Sun.

Answer 12

Kepler’s third law.

Question 13

Venus has a period if revolution of 225 Earth days. Find the distance between the Sun and Venus as multiple of Earth’s average distance from the Sun.

Answer 13

(Te/Tv)^2 = (Re/Rv)^3
365.25/225= Re^3/Rv^3
Rv=^3√ 225rE^3/365.25
Rv= 0.851 Re

Question 14

Identify the name of the law that states: 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 object, squared.

Answer 14

Law of Universal Gravitation.

Question 15

Identify the use of the this description: The period of a planet orbiting the Sun is equal to 2 pi times the square root of the average distance from the Sun cubed, divided by the product of the universal gravitational constant and the mass of the Sun.

Answer 15

Period of a Planet Orbiting the Sun.

Question 16

What force causes an object to move in a circle?

Answer 16

Circular Motion.

Question 17

A runner moving at a speed of 8.8 m/s rounds a bend with a radius of 25 m. What is the centripetal acceleration of the runner?

Answer 17

Ac=(8.8 m/s)^2/25m
Ac=77.44m^2/s^2/25m
Ac= 3.5 m/s^2

Question 18

State Newton’s Second Law for Circular Motion.

Answer 18

The net centripetal force on an object moving in a circle is equal to the object’s mass times the centripetal acceleration.

Question 19

Describe Centripetal acceleration.

Answer 19

Centripetal acceleration always points to the center of the circle. Its magnitude is equal to the square of the speed divided by the radius of motion.

Question 20

What is the direction of the force that acts on clothes spinning in a top-load washing machine?

Answer 20

Centripetal force (towards the center).

Question 21

A 40.0-g stone is whirled horizontally at a speed of 2.2 m/s with a 0.60m long string. What is the tension in the string?

Answer 21

T=(0.40g)(2.2m/s)^2/0.60

T= 0.32N

Question 22

Define uniform circular motion.

Answer 22

The movement of an object at a constant speed around a circle with a fixed radius

Question 23

What is the direction of the centripetral acceleration?

Answer 23

Is a center-seeking acceleration.

Question 24

An airplane traveling at 201 m/s makes a turn. What is the smallest radius of the circular path (in kilometers) the pilot can make and keep the centripetal acceleration under 5.0 m/s2?

Answer 24

r=(201m/s)^2/(50m/s^2)
r=40401m^2/s^2/5 m/s^2
r= 8.1 km

Question 25

What is the equation for kinetic energy?- Identify

Answer 25

K.E. = 1/2 m v2

Question 26

In the equation for kinetic energy, Where’s the speed variable? -Identify

Answer 26

1/2mv^2, v is the speed variable

Question 27

A elephant kicks a 5.0kg stone with 150J of kinetic energy.

What is the stone’s speed? - Calculation

Answer 27

Final Answer= 7.7 m/s
Procedure

K=1/2mv2
v2= 2K/m
Square root of 2(150J) / 5.0kg = square root of 60m2/s2
= 7.7 m/s

Question 28

A 30kg dog runs at a speed of 15 m/s.

What is the dog’s kinetic energy? -Calculation

Answer 28

Final answer= 3,375 J
Procedure
K=1/2mv2
1/2(30kg)(15m/s)2
=3,375J

Question 29

A brown bear runs at a speed of 9.0m/s with 23,000J of kinetic energy.
What is the bear’s mass. - Calculation

Answer 29

Final answer= 570kg
Procedure

K= 1/2mv2
m= 2K/v2

=2(23000J)/ (9,0m/s)2
=570kg

Question 30

A 54kg pig runs at a speed of 1.0 m/s.

What is the pig’s kinetic energy? -Calculation

Answer 30

Final Answer= 27J
Procedure

K=1/2mv2
= 1/2 (54kg)(1.0m/s)2
=27J