LE 3

Question 1

True or False: the potential energy of the body increases when an object is being lifted and the work done by its weight is positive

Answer 1

False (it should be decreases)

Question 2

True or False: kinetics is the study of geometry in motion

Answer 2

False

Question 3

True or False: when a problem involves two particles or more, the principle of work and energy can be applied to each particle separately

Answer 3

True

Question 4

when the relation existing between the position coordinates of several particles is linear, a similar relations holds between the velocities and between the accelerations of the particles

Answer 4

dependent motion

Question 5

True or False: the coefficient of restitution is zero when there is a perfect elastic impact

Answer 5

False (it should be 1)

Question 6

True or False: particles that in oblique central impact are assumed to be perfectly smooth and frictionless

Answer 6

True

Question 7

when a mechanical system involve friction, its total mechanical energy _____________________

Answer 7

decreases

Question 8

if the resultant force acting on a particle is not zero, the particle will have ______________________ proportional to the magnitude of the resultant and in the direction of this resultant force

Answer 8

an acceleration

Question 9

True or False: instantaneous acceleration can never be equal to average acceleration (if both started at zero)

Answer 9

False

Question 10

the moment about a point of the vector mv is called?

Answer 10

moment of momentum

Question 11

when the only force acting on particle P is a force F directed toward or away from a f0xed-point O, the particle is said to be moving under _____________

Answer 11

a central force

Question 12

True or False: the work of weight is the product of weight and the vertical displacement of the center of gravity of the body

Answer 12

True

Question 13

True or False: normal acceleration is always directed toward the center of curvature of the path

Answer 13

True

Question 14

True or False: the fix point wherein the only force acting on a particle is directed, moving under a central force is called the center of force

Answer 14

True

Question 15

True or False: when a particle moves under a central force, the angular momentum of the particle about the center of force is zero

Answer 15

False (it should be constant)

Question 16

the relative velocity of the two particles after impact can be obtained by multiplying their __________________ before impact by the coefficient of restitution

Answer 16

relative velocity

Question 17

True or False: the principle of work and energy can be used to directly determine the acceleration of the particle

Answer 17

False (it should be cannot)

Question 18

the system of the external forces and the systems of the effective forces are equipollent if they have the same _____________ and the same _______________

Answer 18

resultant, moment

Question 19

True or False: in a dynamic equilibrium system, there exists a net force and the translational and the rotational velocities exist but are constant

Answer 19

False (there is no net force dapat)

Question 20

engineering mechanics; displacement, velocity, acceleration; without reference to the cause of motion

Answer 20

kinematics

Question 21

when a particle moves from an initial position to final position under the action of a force, the work of that force is equal to the change in the kinetic energy of the particle. this is known as the?

Answer 21

principle of work and energy

Question 22

the study of the relation between the forces on a body, its mass, and its motion

Answer 22

kinetics

Question 23

True or False: the kinetic energy of a system of particles is the sum of the kinetic energies of the various particles of the system

Answer 23

True

Question 24

the energy that is stored in an object due to its position relative to a certain reference

Answer 24

potential energy

Question 25

True or False: in a multiple pulley system, the summation of displacements between bodies in motion with respect to an axis of reference is zero

Answer 25

True

Question 26

True or False: equipollent means equivalent only when the system of forces is acting on a set of independent particles

Answer 26

False (it should be dependent)

Question 27

coefficient of restitution depend on?

Answer 27

1. the materials involved 2. how much energy is lost during the collision

Question 28

projectile motion has _______________ and _______________

Answer 28

constant vertical acceleration constant horizontal velocity

Question 29

a collision between two bodies which occurs in a very small interval of time and during which the two bodies exert relatively large forces on each other

Answer 29

impact

Question 30

True or False: angular momentum can only be resolved to its polar components

Answer 30

False (it should be linear)

Question 31

coefficient of restitution does not depend on?

Answer 31

The mass of the colliding bodies

Question 32

the _____________ of a particle is characterized by specifying the particle's position, velocity, and acceleration at any given instant

Answer 32

kinematics

Question 33

True or False: the linear momentum of a particle moving under a central force is constant, i both magnitude and direction

Answer 33

False (it should be angular)

Question 34

True or False: if the resultant force acting on a particle is zero, the linear momentum of the particle remains constant in both magnitude and direction

Answer 34

True

Question 35

if polar coordinates are used, we resolve the _________ of the particle into radial and transverse component

Answer 35

linear momentum

Question 36

a force acting on a particle during a very short time interval that is large enough to produce definite change in momentum is called _______________

Answer 36

an impulsive force

Question 37

if no ____________ acts on the particles of a system, the linear momentum, and the angular momentum about an origin of the system of particles are conserved

Answer 37

external force

Question 38

True or False: if the acceleration of the particle is zero for every value of t, it can be concluded that the velocity is also zero

Answer 38

False

Question 39

the energy transferred to or from an object via application of force along a displacement

Answer 39

work

Question 40

True or False: in the principle of work and energy, forces which do not work are eliminated from the solution of the problem

Answer 40

True

Question 41

the resultant of the ___________ acting on the particle is equal to the rate of change of the linear momentum of the particle

Answer 41

forces