physics energy and work mops

how is work calculated

w = change in ME w= change in PE + change in KE w= F parallel distance w= fgh

A 42-kg object is moving with a speed of 1.2 m/s at a height of 4.1 m. The kinetic energy of the object is _______.

30.2 J 1.2 ^2 = 1.44 x 42 = 60.48 /2 = 30.2

A 54-kg object is moving with a speed of 7.6 m/s at a height of 5.7 m. The potential energy of the object is __________.

3016 J 54 x 9.8 x 5.7 = 3016

If an object has kinetic energy, then it will not have any potential energy. Select one: True False

False

what is work

a force exerted on an object through distance work is done when a force acts on an object and object moves in the direction of the force

Which of the following variations will increase the potential energy of an object? Select one or more: a. Increase the object's mass. b. Increase the object's height. c. Decrease the object's speed. d. Increase the object's speed. e. Decrease the object's height. f. Decrease the object's mass.

a. Increase the object's mass. b. Increase the object's height.

Some forces are categorized as conservative forces (or internal forces) while others are categorized as non-conservative forces (or external forces). Which of the following forces are generally categorized as conservative (or internal) forces? Select one or more: a. Spring Force b. Air Resistance Force c. Force of Gravity d. Normal Force e. Force of Friction f. Applied Force g. Tension Force

a. Spring Force c. Force of Gravity

An object will have kinetic energy if it is _____. Select one or more: a. moving on the ground (height = 0 m) b. at rest on the ground (height = 0 m) c. moving above the ground (a non-zero height) d. at rest above the ground (a non-zero height) e. moving f. at rest

a. moving on the ground (height = 0 m) c. moving above the ground (a non-zero height) e. moving

unit for work =

Joule

In order to have work done upon an object, there must be a(n) ____ to cause a(n) ____. Select one: a. impulse imparted to the object, velocity change b. force acting upon the object, displacement c. force acting upon the object, acceleration d. impulse imparted to the object, displacement e. impulse imparted to the object, acceleration f. force acting upon the object, velocity change

b. force acting upon the object, displacement

In order for an object to conserve its total mechanical energy it is absolutely necessary that ____. Select one or more: a. conservative (i.e., internal) forces do work upon the object b. non-conservative (i.e., external) forces do NOT do net work upon the object c. conservative (i.e., internal) forces act upon the object d. non-conservative (i.e., external) forces do NOT act upon the object e. all the forces acting upon the object are balanced

b. non-conservative (i.e., external) forces do NOT do net work upon the object

Work is a ____ quantity; it is fully described by stating its ____. Select one: a. vector, magnitude and direction b. scalar, magnitude alone c. scalar, magnitude and direction d. vector, magnitude alone e. ... nonsense! Work is simply a concept and not a quantity.

b. scalar, magnitude alone

Which of the following are examples of work being done (either positive or negative) upon an object? Select one or more: a. A force is applied to an object to hold it at rest on an inclined plane. b. An upward force is applied to an object to suspend it motionless in mid-air. c. An upward force is applied to an object to move it upward at a constant speed. d. A rightward force is applied to an object to move it to the right at a constant speed. e. A rightward force is applied to an object to accelerate it to the right. f. An upward force is applied to an object to accelerate it upward. g. An upward force is applied to a downward moving object to slow it down as it moves.

c. An upward force is applied to an object to move it upward at a constant speed. d. A rightward force is applied to an object to move it to the right at a constant speed. e. A rightward force is applied to an object to accelerate it to the right. f. An upward force is applied to an object to accelerate it upward. g. An upward force is applied to a downward moving object to slow it down as it moves.

An object will definitely have potential energy if it is _____. Select one or more: a. moving b. moving on the ground (height = 0 m) c. moving above the ground (a non-zero height) d. at rest above the ground (a non-zero height) e. at rest f. at rest on the ground (height =

c. moving above the ground (a non-zero height) d. at rest above the ground (a non-zero height)

Which of the following variations will increase the kinetic energy of an object? Select one or more: a. Decrease the object's speed. b. Increase the object's height. c. Decrease the object's mass. d. Decrease the object's height. e. Increase the object's speed. f. Increase the object's mass.

e. Increase the object's speed. f. Increase the object's mass.

If the total mechanical energy of an object is conserved, then ____. Select one or more: a. there is neither any KE nor PE in either the initial or the final state b. the total amount of KE and PE gradually decreases to 0 Joules c. the initial amount of KE equals the final amount of PE d. the sum of the kinetic energy (KE) and the potential energy (PE) is 0 Joules e. the sum of the KE and the PE is the same for the initial state as it is for the final

e. the sum of the KE and the PE is the same for the initial state as it is for the final

Kinetic energy is the energy that an object possesses due to its ____ and potential energy is the energy that an object possesses due to its ____. Select one: a. mass, motion b. acceleration, mass c. motion, lack of motion d. position, motion e. position, lack of position f. motion, position g. lack of position, position h. lack of motion, motion i. motion , mass j. mass, acceleration

f. motion, position

If an object has potential energy, then its kinetic energy is 0 J. Select one: True False

false

If an object is moving above the ground (at a non-zero height), then it will not have any potential energy. Select one: True False

false

If an object is moving along the ground, then it will not have any kinetic energy. Select one: True False

false

Suppose that an object moves upward with an increasing speed. In this situation, the object's kinetic energy would_______, its potential energy would ________ , and its total mechanical energy would ________.

increase, increase, increase

friction is positive or negative work

negative

If the only forces doing work upon an object are conservative (or internal) forces, then the total mechanical energy of the object will __________________If the only forces doing work upon an object are non-conservative (or external) forces, then the total mechanical energy of the object will _________________

not change; change either increase or decrease

positive work vs negative work

positive- objects gains energy - energy is being transferred to object negative- object is losing energy - energy transferred from object to surroundings

Suppose that an object moves downward at a constant speed. In this situation, the object's kinetic energy would _______, its potential energy would ______, , and its total mechanical energy would _______.

remain the same, decrease, decrease

what is energy

the ability an object has to produce or change in itself or its surroundings in terms of state in motion

what is mechanical energy

the energy an object has due to its motion or position energy due to work done on an object