Page 45 - Science Course 2 (Book 2)

Mo9-L1b: How are Energy and Work Related?

Work also depends on the distance an object moves
during the time the force is applied.
Math Skills Work Equation

The equation for work is shown below.
Solve for Work:
A student lifts a bag from the f oor his or her
shoulder 1.2m above the f oor, using a force of 50 N.
How much work does the student do on the bag?

1. This is what you know:
force: F = 50N
Force is the force applied to the object. Distance is distance: d = 1.2m
the distance the object moves in the direction of the
force while the force is acting on it. 2. This is what you need to f nd:
acceleration: W
The force in the equation is in newtons, and distance
is in meters. 3. Use this formula:
W = Fd
The product of newtons and meters is newton-meter.
4. Substitute:
A newton-meter is a joule. W = (50N) X (10N) = 60N–m = 60J
The values for F and d into the formula and
multiply.

Answer: The amount of work done is 60J

Energy and Heat

Friction is a force between two surfaces in contact
with each other.

The direction of friction is in the opposite direction
of the motion.

An object has mass, which is the total amount of
material it is made of measured in kilograms.
Mass is not a force.

We measure forces in newtons using a force meter,
also known as a newton meter.

The word newton comes from Sir Isaac Newton,
who f rst put together ideas about forces.

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