1. Unit IV, Worksheet 5 Name_______________________________
Weight and Mass & Forces in Equilibrium Date__________________Period________
In the physical sciences, mass (measured in kilograms, kg, or grams, g) and weight
(measured in newtons, N) are different properties. Mass is a measure of the amount of
matter in the body while weight is a measure of the force on the object caused by a
gravitational field. Your mass then, would remain the same if you went to the moon, but
your weight would change because there is less gravity on the moon’s surface.
On Earth, 1 kg of mass weighs
approximately 10 N.
1 kg = 1000 g
1. In the picture above, is the scale measuring mass or weight? Explain.
2. An object has a mass of 8.00 kg. What is the gravitational force on the object by the
earth? (Show your work.)
3. An object has a mass of 250 g. What is the gravitational force of on the object by the
earth? (Show your work.)
4. The earth exerts a gravitational force of 500 N on an object. What is the mass of the
object in kg? (Show your work.)
5. The earth exerts a gravitational force of 0.500 N on an object. What is the mass of
the object in g? (Show your work.)

2. When in equilibrium (at rest or at constant velocity), the total force or net force (Fnet) on
an object is equal to zero. Fnet is the vector sum of all the forces on an object. For each of
the problems below, identify the system and then carefully draw a force diagram for the
system. Only after your have drawn the force diagram, use the standard problem solving
format to determine the required quantities.
6. A grocery bag is capable of exerted an upward force of 45N
before breaking. Can 5 kg of groceries be lifted at a constant
velocity in this bag without ripping? Calculate the normal
force the bag would have to exert on the groceries.
7. The plastic bag to the right holds 2.5 kg of food. What is
the tension in each handle when it is held up at rest?
5kg
2.5 kg
TBSTBS
WBE
2kg
Find the tension in the each of the
two strings supporting the ball.
Fnet = 0 so TBS+ TBS = WBE
WBE = (2kg)(10N/kg) = 20N
TBS+ TBS = 2 TBS= 20N
so TBS= 10N

3. 8. The spider is hanging at rest from a thread that has a
tension of 0.10 N. What is the mass of the spider?
9. The person and the sled have a weight of
1500 N. The dogs must exert a combined
horizontal force of 300 N to pull the sled
at constant velocity. Find the normal
force and the force of friction on the sled.
10. A pendant hangs from chains that make a 90 degree angle to each other as shown in
the diagram. If the tension on the left side is 4N and the tension on the right side is
3N, find the weight of the heart pendant.
T=0.10N
300N
1500N
4N
3N