NSCI 101-001 Chapter: 4 with comprehensive Questions and
Answers
You exert a force on a ball when you toss it upward. How long does that force last after the ball
leaves your hand?✔️✔️The force you exert on the ball ceases as contact with your hand ceases
On a long alley, a bowling ball slows down as it rolls. Is any horizontal force acting on the ball?
How do you know?✔️✔️Yes, if the ball slows down, a force opposite to its motion is acting -
likely air resistance and friction between the ball and the alley.
If a motorcycle moves with a constant velocity, can you conclude that there is no net force acting
on it? How about with constant acceleration?✔️✔️Constant velocity means zero acceleration, so
yes, no net force acts on the motorcycle but when moving at constant acceleration there is a net
force acting on it.
Since an object's weighs less on the surface of the moon than on the Earth's surface, does it have
less inertia on the moon's surface?✔️✔️No, inertia involves mass not weight.
Which contains more apples: a 1-pound bag of apples on Earth or a 1-pound bag of apples on the
Moon? Which contains more apples: a 1-kilogram bag of apples on Earth or a 1-kilogram bag of
apples on the moon?✔️✔️Items like apples weigh less on the moon, so there are more apples in a
1-pound bag of apples there. Mass is another matter, for the same quantity of apples are in 1-kg
bag on the Earth and on the Moon.
If gold were sold by weight, would you rather buy it in Denver or Death Valley? If it were sold
by mass, which of these locations makes the best buy? Defend your answers.✔️✔️Buy by weight
in Denver because the acceleration of gravity is less in Denver than in Death Valley. Buying by
mass would be the same amount in both locations.
In an orbiting space vehicle, you are handed two identical boxes, one filled with sand and the
other filled with feathers. How can you determine which is which without opening the
boxes?✔️✔️Shake the boxes. The box that offers the greater resistance to acceleration is the more
massive box, the one containing the sand.
, Your empty hand does not hurt when it bangs lightly against a wall. Why does it hurt if you're
carrying a heavy load? Which of Newton's laws is most applicable here?✔️✔️When you carry a
heavy load there is more mass involved and a greater tendency to remain moving. If a load in
your hand moves toward a wall, its tendency is to remain moving when contact is made. This
tends to squash your hand if it is between the load and the wall-an unfortunate example of
Newton's first law in action.
Does the mass of an astronaut change when he or she is visiting the International Space Station?
Defend your answer.✔️✔️Mass is a measure of the amount of matieral in something, not
gravitational pull depends on its location. So although the weight of the astronaut may change
with location, mass does not.
Why does a massive cleaver more effective for chopping vegetables than and equally sharp
knife?✔️✔️A massive cleaver is more effective in chopping vegetables because its greater mass
contributes to greater tendency to keep moving as the cleaver chops the food.
When a junked car is crushed into a compact cube, does its mass change? Its weight?
Explain.✔️✔️Neither the mass nor the weight of a junked car changes when it is crushed. What
does change is its volume, not to be confused with mass and weight.
Gravity on the surface of the Moon is only 1/6 as strong as gravity on Earth. What is the weight
of a 10-kg object on the Moon and on the Earth? What is its mass on each?✔️✔️10 kilograms
weight about 100 N on the Earth (weight = mg = 10kg X 10 m/s^2 = 100 N or 98 N if g = 9.8
m/s^2 is used) On the moon the weight is 1/6 of 100 N = 16.7 N (or 16 N if g = 9.8 m/s^2 is
used). The mass is 10 kg everywhere.
What happens to the weight reading on a scale you stand on when you toss a heavy object
upward?✔️✔️The scale reading will increase during the throw. Your upward force on the heavy
object is transmitted to the scale.
What weight change occurs when your mass increases by 2 kg?✔️✔️The change of weight is the
change of mass times g, so when mass changes by 2 kg, weight changes by about 20 N.
Answers
You exert a force on a ball when you toss it upward. How long does that force last after the ball
leaves your hand?✔️✔️The force you exert on the ball ceases as contact with your hand ceases
On a long alley, a bowling ball slows down as it rolls. Is any horizontal force acting on the ball?
How do you know?✔️✔️Yes, if the ball slows down, a force opposite to its motion is acting -
likely air resistance and friction between the ball and the alley.
If a motorcycle moves with a constant velocity, can you conclude that there is no net force acting
on it? How about with constant acceleration?✔️✔️Constant velocity means zero acceleration, so
yes, no net force acts on the motorcycle but when moving at constant acceleration there is a net
force acting on it.
Since an object's weighs less on the surface of the moon than on the Earth's surface, does it have
less inertia on the moon's surface?✔️✔️No, inertia involves mass not weight.
Which contains more apples: a 1-pound bag of apples on Earth or a 1-pound bag of apples on the
Moon? Which contains more apples: a 1-kilogram bag of apples on Earth or a 1-kilogram bag of
apples on the moon?✔️✔️Items like apples weigh less on the moon, so there are more apples in a
1-pound bag of apples there. Mass is another matter, for the same quantity of apples are in 1-kg
bag on the Earth and on the Moon.
If gold were sold by weight, would you rather buy it in Denver or Death Valley? If it were sold
by mass, which of these locations makes the best buy? Defend your answers.✔️✔️Buy by weight
in Denver because the acceleration of gravity is less in Denver than in Death Valley. Buying by
mass would be the same amount in both locations.
In an orbiting space vehicle, you are handed two identical boxes, one filled with sand and the
other filled with feathers. How can you determine which is which without opening the
boxes?✔️✔️Shake the boxes. The box that offers the greater resistance to acceleration is the more
massive box, the one containing the sand.
, Your empty hand does not hurt when it bangs lightly against a wall. Why does it hurt if you're
carrying a heavy load? Which of Newton's laws is most applicable here?✔️✔️When you carry a
heavy load there is more mass involved and a greater tendency to remain moving. If a load in
your hand moves toward a wall, its tendency is to remain moving when contact is made. This
tends to squash your hand if it is between the load and the wall-an unfortunate example of
Newton's first law in action.
Does the mass of an astronaut change when he or she is visiting the International Space Station?
Defend your answer.✔️✔️Mass is a measure of the amount of matieral in something, not
gravitational pull depends on its location. So although the weight of the astronaut may change
with location, mass does not.
Why does a massive cleaver more effective for chopping vegetables than and equally sharp
knife?✔️✔️A massive cleaver is more effective in chopping vegetables because its greater mass
contributes to greater tendency to keep moving as the cleaver chops the food.
When a junked car is crushed into a compact cube, does its mass change? Its weight?
Explain.✔️✔️Neither the mass nor the weight of a junked car changes when it is crushed. What
does change is its volume, not to be confused with mass and weight.
Gravity on the surface of the Moon is only 1/6 as strong as gravity on Earth. What is the weight
of a 10-kg object on the Moon and on the Earth? What is its mass on each?✔️✔️10 kilograms
weight about 100 N on the Earth (weight = mg = 10kg X 10 m/s^2 = 100 N or 98 N if g = 9.8
m/s^2 is used) On the moon the weight is 1/6 of 100 N = 16.7 N (or 16 N if g = 9.8 m/s^2 is
used). The mass is 10 kg everywhere.
What happens to the weight reading on a scale you stand on when you toss a heavy object
upward?✔️✔️The scale reading will increase during the throw. Your upward force on the heavy
object is transmitted to the scale.
What weight change occurs when your mass increases by 2 kg?✔️✔️The change of weight is the
change of mass times g, so when mass changes by 2 kg, weight changes by about 20 N.
