Ch 4-6

Question 1

whenever one body exerts a force on a second body, the first body experiences a force that is equal in magnitude and opposite in direction to the force that the first body exerts

Answer 1

Newton’s third law of motion

Question 2

When objects rest on a surface, the surface applies a force to the object that supports the weight of the object. This supporting force acts perpendicular to and away from the surface

Answer 2

Normal Force

Question 3

N=mg.

Answer 3

Normal force is related to mass x gravity when it sits there.

Question 4

Hooke’s law is given by….

Answer 4

F=kΔL or F=kΔx

Question 5

Tension

Answer 5

the pulling force that acts along a medium, especially a stretched flexible connector, such as a rope or cable; when a rope supports the weight of an object, the force on the object due to the rope is called a tension force.

Question 6

is friction proportional to normal force?

Answer 6

yes

Question 7

friction

Answer 7

a force that opposes relative motion or attempts at motion between systems in contact

Question 8

kinetic friction

Answer 8

a force that opposes the motion of two systems that are in contact and moving relative to one another

Question 9

static friction

Answer 9

a force that opposes the motion of two systems that are in contact and are not moving relative to one another

Question 10

centripetal acceleration

Answer 10

the acceleration of an object moving in a circle, directed toward the center

Question 11

centripetal force

Answer 11

any net force causing uniform circular motion

Question 12

Newton’s universal law of gravitation is…

Answer 12

Every particle in the universe attracts every other particle with a force along a line joining them. The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. In equation form, this is
Fg=Gm1m2r2, Fg=Gm1m2r2,

Question 13

gravitational constant, G

Answer 13

a proportionality factor used in the equation for Newton’s universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe

Question 14

work-energy theorem

Answer 14

the result, based on Newton’s laws, that the net work done on an object is equal to its change in kinetic energy

Question 15

gravitational potential energy

Answer 15

the energy an object has due to its position in a gravitational field

Question 16

Mechanical energy is defined as….

Answer 16

KE + PE

Question 17

conservative force

Answer 17

a force that does the same work for any given initial and final configuration, regardless of the path followed

Question 18

potential energy

Answer 18

energy due to position, shape, or configuration

Question 19

conservation of mechanical energy

Answer 19

the rule that the sum of the kinetic energies and potential energies remains constant if only conservative forces act on and within a system

Question 20

potential energy of a spring

Answer 20

the stored energy of a spring as a function of its displacement; when Hooke’s law applies, it is given by the expression
1/2=kx^212kx2
where x is the distance the spring is compressed or extended and k is the spring constant

Question 21

nonconservative force

Answer 21

a force whose work depends on the path followed between the given initial and final configurations

Question 22

Define Power

Answer 22

the rate which is when work is done P = W/t.

Question 23

What is the unit for power?

Answer 23

Watts

Question 24

To solve problems involving Newton’s laws of motion, follow the procedure described:

Answer 24

Draw a sketch of the problem.
Identify known and unknown quantities, and identify the system of interest. Draw a free-body diagram, which is a sketch showing all of the forces acting on an object. The object is represented by a dot, and the forces are represented by vectors extending in different directions from the dot. If vectors act in directions that are not horizontal or vertical, resolve the vectors into horizontal and vertical components and draw them on the free-body diagram.
Write Newton’s second law in the horizontal and vertical directions and add the forces acting on the object. If the object does not accelerate in a particular direction (for example, the x-direction) then Fnetx = 0. If the object does accelerate in that direction, Fnetx = ma.
Check your answer. Is the answer reasonable? Are the units correct?