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Force and Work
R. A. Hart, 13 Feb 1991 (by permission)
Chapter 10, Merrill General Science, 1986
When an object is at rest
all forces are balanced
the sum of forces is zero
only gravity is acting on the object
no forces are acting on the object
it has high kinetic energy
it is doing work
The fundamental forces can be classified into:
all of the above
electromagnetic
gravitational
nuclear
none of the above
Moving electric charges produce
magnetic forces
electric forces
potential energy
kinetic energy
all of the above
Stationary charged particles
all of the above
produce electric forces
repel if of like charge
attract if of unlike charge
none of the above
Frictional forces are:
electric forces
magnetic forces
gravitational forces
nuclear forces
kinetic forces
All forces are able to:
act over a distance
exert a force without two objects coming in contact
act if the object can be touched
produce energy
do work on non-moving objects
all of the above
A force of attraction exists between any two objects due to their:
masses
weight
gravity
acceleration
newtons
The force required to accelerate a one-kilogram mass at the rate of one meter per second squared:
newton
joule
pascal
watt
all of the above
The gravitational force between two objects:
is proportional to the masses of the objects
is equal to the summ of the masses of the objects
is equal to the difference in masses of the objects
increases with the distance between the objects
none of the above
The strongest forces are:
nuclear
electromagnetic
gravitational
depends on the distance between objects
all are about equal
A region of space in which a force has a definite value at every point:
a field
a fulcrum
a newton
a joule
a pascal
A measure of gravitational force:
weight
mass
kilogram
joule
watt
Weight is measured in:
newtons
joules
pascals
watts
all of the above
A pressure of one newton per square meter is a:
pascal
joule
watt
all of the above
none of the above
Force per unit area:
pressure
work
energy
power
momentum
The result of a force applied through a distance:
work
energy
pascal
watt
newton
Work is measured in:
newton-meters
joules
watts
pascals
all of the above
none of the above
The ability to do work:
energy
watt
newton
pascal
all of the above
Energy is measured in:
joules
the same unit as work
pascals
watts
newtons
all of the above
The total amount of energy in an isolated system:
remains the same
decreases over time
increases in the day time
decreases in winter
none of the above
Energy can be:
changed from one form to another
created
destroyed
created and destroyed
A form of energy is:
all of the above
chemical
electric
nuclear
solar
The energy of motion:
kinetic
potential
watt
joule
newton
The kinetic energy of an object is equal to multiplying:
one half its mass by the square of its velocity
newtons by the distance traveled
its mass by velocity by time
its mass by acceleration due to gravity by height
The potential energy of an object is equal to multiplying:
its mass by acceleration due to gravity by height
its mass by velocity by time
one half its mass by the square of its velocity
newtons by the distance traveled
none of the above
The energy of position is called:
potential
kinetic
gravity
acceleration
field
Machines are used to:
change the direction of a force
change the magnitude of an applied force
increase the amount of work done
reduce the amount of energy needed
improve efficiency
improve power output
The measure of how much a machine changes a force:
mechanical advantage
force exerted by machine/force applied to machine
efficiency
work output/work input
work/time
none of the above
The measure of the amount of work output compared to the work put into the machine:
efficiency
power
mechanical advantage
momentum
none of the above
The amount of work done during a given time period:
power
momentum
efficiency
energy
The work done at one joule per second:
watt
pascal
newton
calorie
Calorie
Momentum is the product of:
mass times velocity
work times time
mass times acceleration
force times distance
force times area