Chem 108 - Physical Science 14th edition - Ch 3

The law of conservation of linear momentum may be stated as follows:

The total linear momentum of an isolated system remains the same if there is no external, unbalanced force acting on the system.

newton (N)

The unit of force in the metric system; 1 kg·m/s^2. (3.3)

9. Newton's third-law force pair acts on ___ objects. (3.4)

different

Third Law, acting on:

different objects

Figure 3.22 Torque and Lever Arm

(a) Torque varies with the length of the lever arm r. (b) When the length of the lever arm is doubled for a given force, the torque is doubled. Thus, by using a longer wrench, more torque can be applied to a bolt or nut.

k. ____ Capable of producing motion or a change in motion

1. force

j. ____ Action and reaction

10. Newton's third law of motion

c. ____ Describes the force of gravity

11. Newton's law of universal gravitation

l. ____ Universal constant

12. G

p. ____ Required for an object to float

13. buoyant force

a. ____ Gives the magnitude of the buoyant force

14. Archimedes' principle

g. ____ Mass × velocity

15. linear momentum

d. ____ Occurs in the absence of an unbalanced force

16. law of conservation of linear momentum

o. ____ mvr

17. angular momentum

r. ____ Changes angular momentum

18. torque

i. ____ Conservation law requiring the absence of an unbalanced torque

19. law of conservation of angular momentum

b. ____ A measure of inertia

5. mass

h. ____ F = ma

6. Newton's second law of motion

m. ____ SI unit of force

7. newton

q. ____ mg

8. weight

f. ____ Resistance to relative motion

9. friction

Figure 3.14 The Amount of Mass Makes a Difference

A 1.0-kg mass and a 2.0-kg mass separated by a distance of 1.0 m have a negligible mutual gravitational attraction (about 10−10 N). However, because the Earth's mass is quite large, the masses are attracted to the Earth with forces of 9.8 N and 19.6 N, respectively. These forces are the weights of the masses.

weight

A measure of the force due to gravitational attraction (w = mg, on the Earth's surface). (3.3)

mass

A quantity of matter and a measure of the amount of inertia that an object possesses. (1.4, 3.2)

Figure 3.21 Torque

A torque is a twisting action that produces rotational motion or a change in rotational motion. Torque is analogous to a force producing linear motion or a change in linear motion. The forces F1 and F2 supply the torque.

Archimedes' principle

An object immersed wholly or partially in a fluid experiences a buoyant force equal in magnitude to the weight of the volume of fluid that is displaced. (3.6)

Newton's first law of motion

An object will remain at rest or in uniform motion in a straight line unless acted on by an external, unbalanced force. (3.2)

Newton's law of universal gravitation

Every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them; F = Gm1m^2/r^2. (3.5)

Newton's third law of motion

For every action there is an equal and opposite reaction; for every force there is an equal and opposite force, acting on different bodies. (3.4)

12. Milk is ___ dense than the cream that floats on top. (3.7)

More

Figure 3.17 The Tip of the Iceberg

The majority of a floating iceberg is beneath the water, as illustrated here. Approximately 90% of its bulk is submerged. The displacement of water by the submerged portion gives rise to a buoyant force that equals the iceberg's weight.

inertia

The natural tendency of an object to remain in a state of rest or in uniform motion in a straight line. (3.2)

linear momentum

The product of an object's mass and its velocity. (3.7)

unbalanced (net) force

The sum of vector forces with a nonzero result. A force capable of producing motion. (3.1)

acceleration due to gravity is relatively constant (g = 9.80 m/s2)

What is the weight (in newtons) of a 1.0-kg mass on the Earth w=mg=(1.0kg)(9.8m/s2)=9.8N

Figure 3.19 An Internal Force and Conservation of Linear Momentum

When the string is burned, the compressed spring applies an internal force to the system. See Example 3.4.

Figure 3.18 Conservation of Linear Momentum

When the system is at rest, the total momentum of the system (man and boat) is zero. When the man jumps toward the shore (an internal force), the boat moves in the opposite direction, conserving linear momentum.

First Law, also called law of:

inertia

6. According to Newton's second law, an object's acceleration is ___ proportional to its mass. (3.3)

inversely

Archimedes' principle: buoyant force - An object will sink if

its average density is greater than the density of the fluid (ρo > ρf)

7. The newton unit of force is equal to ___ in standard units. (3.3)

kg·m/s2

Second Law, units of effect:

m/s^2

5. The inertia of an object is related to its ___. (3.2)

mass

First Law, a measure of inertia:

mass

Second Law, cause:

net force

There is also a conservation law for angular momentum.

states that the angular momentum of an object remains constant if there is no external, unbalanced torque acting on it.

14. The angular momentum of an object is not conserved if the object is acted upon by unbalanced ___. (3.7)

torque

10. G is thought to be a(n) ___ gravitational constant. (3.5)

universal

2. Forces are ___ quantities. (3.1)

vector

Figure 3.6 Force, Mass, and Acceleration

(a) An unbalanced force F acting on a mass m produces an acceleration a. (b) If the mass remains the same and the force is doubled, then the acceleration is doubled. (c) If the mass is doubled and the force remains the same, then the acceleration is reduced by one-half. The friction of the cars is neglected in all cases.

10. What is true about the constant G? (3.5) (a) It is a very small quantity. (b) It is a force. (c) It is the same as g. (d) It decreases with altitude.

(a) It is a very small quantity.

5. According to Newton's second law of motion, when an object is acted upon by an unbalanced force, what can be said about the acceleration? (3.3) (a) It is inversely proportional to the object's mass. (b) It is zero. (c) It is inversely proportional to the net force. (d) It is independent of mass.

(a) It is inversely proportional to the object's mass.

s. ____ Law of inertia

3. Newton's first law of motion

n. ____ Tendency of an object to remain at rest or in uniform, straight-line motion

4. inertia

force

A vector quantity capable of producing motion or a change in motion, that is, a change in velocity or an acceleration. (3.1)

EXAMPLE 3.3 Applying Newton's Law of Gravitation Two objects with masses of 1.0 kg and 2.0 kg are 1.0 m apart (Fig. 3.14). What is the magnitude of the gravitational force between these masses?

Solution The magnitude of the force is given by Eq. 3.4: F=G m1 m2 r2 =(6.67×10^−11 N⋅m^2/kg^2)(1.0kg)(2.0kg)(1.0m)^2 =1.3×10^−10 N

Figure 3.10 Acceleration Due to Gravity

The acceleration due to gravity is independent of the mass of a freely falling object. Thus, the acceleration is the same for all such falling objects. An object with two times the mass of another has twice the gravitational force acting on it, but it also has twice the inertia and so falls at the same rate.

conservation of linear momentum, law of

The total linear momentum of an isolated system remains constant or conserved if there is no external, unbalanced force acting on the system. (3.7)

G

The universal gravitational constant; G = 6.67 × 10−11 N·m^2/kg^2. (3.5)

buoyant force

The upward force resulting from an object being wholly or partially immersed in a fluid. (3.6)

Newton's second law of motion:

acceleration = unbalancedforce/mass a = F/m

1. A force is a quantity that is ___ of producing motion or a change in motion. (3.1)

capable

First Law, type of motion:

constant velocity

3. Galileo concluded that objects ___ (could/could not) remain in motion without a net force. (3.2)

could

Archimedes' principle: buoyant force - An object will be in equilibrium at any submerged depth

in a fluid if the average density of the object and the density of the fluid are equal (ρo = ρf)

8. The coefficient of ___ friction is generally greater than the coefficient of ___ friction. (3.3)

static, kinetic or sliding

e. ____ A nonzero vector sum of forces

2. unbalanced, or net, force

Second Law, effect:

acceleration

Figure 3.11 Newton's Third Law in Action

(a) The rocket and exhaust gas exert equal and opposite forces on each other and so are accelerated in opposite directions. (b) The equal and opposite forces are obvious here. Notice the distortion of the racquet strings.

Figure 3.13 Newton's Law of Gravitation

(a) Two particles attract each other gravitationally, and the magnitude of the forces is given by Newton's law of gravitation. The forces are equal and opposite: Newton's third-law force pair. (b) For a homogeneous or uniform sphere, the force acts as though all the mass of the sphere were concentrated as a particle at its center. w=mg=GmME/R2E (using Eq. 3.4).

12. If a submerged object displaces an amount of liquid with a weight less than its own, when the object is released, it will ___. (3.6) (a) sink (b) remain submerged in equilibrium (c) float (d) pop up out of the surface

(a) sink

8. Which is true of the force pair of Newton's third law? (3.4) (a) The two forces never produce an acceleration. (b) The two forces act on different objects. (c) The two forces always cancel each other (d) The two forces are in the same direction.

(b) The two forces act on different objects.

4. A net force can produce ___. (3.3) (a) an acceleration (b) a change in velocity magnitude (c) a change in velocity direction (d) all of the preceding

(b) a change in velocity magnitude

Newton's third law may be written as

F1 = force exerted on object 1 by object 2 − F2 = force exerted on object 2 by object 1 F1 = −F2 or m1 a1 = − m2 a2

Third Law, for every (1):

action

Newton's second law of motion

The acceleration of an object is equal to the net force on the object divided by the mass of the object; a = F/m. (3.3)

Figure 3.20 Angular Momentum

The angular momentum of a comet going around the Sun in an elliptical orbit is given at the two opposite points in the orbit by mv1r1 and mv2r2. Angular momentum is conserved in this case, and mv1r1 = mv2r2. As the comet comes closer to the Sun, the radial distance r decreases, so the speed v must increase. Similarly, the speed decreases when r increases. Thus, a comet moves fastest when it is closest to the Sun and slowest when it is farthest from the Sun, which is also true for the Earth. (The orbit here is exaggerated to show radial differences.)

friction

The ever-present resistance to relative motion that occurs whenever two materials are in contact with each other, whether they are solids, liquids, or gases. (3.3)

11. An object will sink in a fluid if its average density is ___ than that of the fluid. (3.7)

greater

Figure 3.2 Balanced and Unbalanced Forces

a) When two applied forces are equal in magnitude and acting in opposite directions, they are said be balanced, and there is no net force and no motion if the system is initially at rest. (b) When F2 is greater than F1, there is an unbalanced, or net force to the right, and motion occurs.

Archimedes' principle: buoyant force - An object will float in a fluid if

in a fluid if its average density is less than the density of the fluid (ρo < ρf)

angular momentum

mvr for a mass m going at a speed v in a circle of radius r. (3.7)

13. The total linear momentum is not conserved if there is a(n) ___ force acting on the system. (3.7)

net or unbalanced

newton (abbreviated N). This is a derived unit. The standard unit equivalent may be seen from Eq. 3.1 by putting it in standard units:

standard units: force = mass × acceleration = kg × m/s2 = kg · m/s2 = N.

9. Which is true about the acceleration due to gravity? (3.5) (a) It is a universal constant. (b) It is a fundamental property. (c) It decreases with increasing altitude. (d) It is different for different objects in free fall.

(c) It decreases with increasing altitude.

15. Angular momentum is conserved in the absence of which of the following? (3.7) (a) inertia (b) gravity (c) a net torque (d) linear momentum

(c) a net torque

3. What term refers to the tendency of an object to remain at rest or in uniform, straight-line motion? (3.2) (a) mass (b) force (c) inertia (d) external force

(c) inertia

13. If a submerged object displaces a volume of liquid equal to its weight and is then released, what will the object do? (3.6) (a) rise to the surface (b) sink (c) remain at its submerged position

(c) remain at its submerged position

11. A child's toy floats in a swimming pool. The buoyant force exerted on the toy depends on the volume of ___. (3.6) (a) water in the pool (b) the pool (c) the water displaced (d) the toy under water

(c) the water displaced

2. What is a possible state of an object in the absence of a net force? (3.2) (a) at rest (b) constant speed (c) zero acceleration (d) all of the preceding

(d) all of the preceding (a) at rest (b) constant speed (c) zero acceleration

6. Mass is related to an object's ___. (3.3) (a) weight (b) inertia (c) density (d) all of the preceding

(d) all of the preceding (a) weight (b) inertia (c) density

14. A change in linear momentum requires which of the following? (3.7) (a) a change in velocity (b) an unbalanced force (c) an acceleration (d) all of these

(d) all of these (a) a change in velocity (b) an unbalanced force (c) an acceleration

7. For every action force, there is which of the following? (3.4) (a) a net force (b) a friction force (c) an unbalanced force (d) an equal and opposite force

(d) an equal and opposite force

1. A net force ___. (3.1) (a) can produce motion (b) is a scalar quantity (c) is capable of producing a change in velocity (d) both (a) and (c)

(d) both (a) and (c) (a) can produce motion (c) is capable of producing a change in velocity

torque

A twisting action that produces rotational motion or a change in rotational motion. (3.7)

conservation of angular momentum, law of

The angular momentum of an object remains constant or conserved if there is no external, unbalanced torque acting on it. (3.7)

Third Law, there is an (2):

equal and opposite reaction

4. An object will remain at rest or in uniform, straight-line motion if not acted upon by a(n) ___. (3.2)

force