test 2

What is the work done by the force F? F pointing up S pointing to right

If a particle is moved from 1 to 2, the work done on the particle by the force, FR will be

A spring with an unstretched length of 5 in expands from a length of 2 in to a length of 4 in. The work done on the spring is _________ in·lb .

If a spring force is F = 5 s3 N/m and the spring is compressed by s = 0.5 m, the work done on a particle attached to the spring will be

What is the work done by the normal force N if a 10 lb box is moved from A to B ?on a curve B at bottom

Two blocks are initially at rest. How many equations would be needed to determine the velocity of block A after block B moves 4 m horizontally on the smooth surface?

The formula definition of power is ___________.
A) dU / dt B) F  v
C) F  dr/dt D) All of the above.

. Kinetic energy results from _______.
A) displacement B) velocity
C) gravity D) friction

A motor pulls a 10 lb block up a smooth incline at a constant velocity of 4 ft/s. Find the power supplied by the motor.
A) 8.4 ft·lb/s B) 20 ft·lb/s
C) 34.6 ft·lb/s D) 40 ft·lb/s

A twin engine jet aircraft is climbing at a 10 degree angle at 260 ft/s. The thrust developed by a jet engine is 1000 lb. The power developed by the aircraft is
A) (1000 lb)(260 ft/s) B) (2000 lb)(260 ft/s) cos 10
C) (1000 lb)(260 ft/s) cos 10 D) (2000 lb)(260 ft/s)

The power supplied by a machine will always be _________ the power supplied to the machine.
A) less than B) equal to
C) greater than D) A or B

A car is traveling on a level road at 88 ft/s. The power being supplied to the wheels is 52,800 ft·lb/s. Find the combined friction force on the tires.
A) 8.82 lb B) 400 lb
C) 600 lb D) 4.64 x 106 lb

The potential energy of a spring is ________
A) always negative. B) always positive.
C) positive or negative. D) equal to ks.

When the potential energy of a conservative system increases, the kinetic energy _________
A) always decreases. B) always increases.
C) could decrease or D) does not change.
increase.

A force F is said to be conservative if the work done is

The work done by a conservative force ------- ----- on the positions of the particle, and is --------- of its velocity or acceleration

-------- energy is a measure of the amount of work a ---------- force will do when a body changes position.

If the work done by a conservative force on a particle as it moves between two positions is –10 ft·lb, the change in its potential energy is _______
A) 0 ft·lb. B) -10 ft·lb.
C) +10 ft·lb. D) None of the above.

Recall that the work of a spring is U1-2 = -½ k(s22 – s12) and can be either positive or negative. The potential energy of a spring is V = ½ ks2. Its value is __________
A) always negative. B) either positive or negative.
C) always positive. D) an imaginary number!

The principle of conservation of energy is usually ______ to apply than the principle of work & energy.
A) harder B) easier
C) the same amount of work D) It is a mystery

. If the pendulum is released from the
horizontal position, the velocity of its
bob in the vertical position is _____
A) 3.8 m/s. B) 6.9 m/s.
C) 14.7 m/s. D) 21 m/s.

The linear impulse and momentum equation is obtained by integrating the ______ with respect to time.

A) friction force B) equation of motion
C) kinetic energy D) potential energy

Which parameter is not involved in the linear impulse and momentum equation?

A) Velocity B) Displacement
C) Time D) Force

Calculate the impulse due to the force.
A) 20 kg·m/s B) 10 kg·m/s
C) 5 N·s D) 15 N·s

A constant force F is applied for 2 s to change the particle’s velocity from v1 to v2. Determine the force F if the particle’s mass is 2 kg.
A) (17.3 j) N B) (–10 i +17.3 j) N
C) (20 i +17.3 j) N D) ( 10 i +17.3 j) N

Jet engines on the 100 Mg VTOL aircraft exert a constant vertical force of 981 kN as it hovers. Determine the net impulse on the aircraft over t = 10 s.
A) -981 kN·s B) 0 kN·s
C) 981 kN·s D) 9810 kN·s

A 100 lb cabinet is placed on a smooth surface. If a force of a 100 lb is applied for 2 s, determine the net impulse on the cabinet during this time interval.
A) 0 lb·s B) 100 lb·s
C) 200 lb·s D) 300 lb·s

The internal impulses acting on a system of particles always __________
A) equal the external impulses. B) sum to zero.
C) equal the impulse of weight. D) None of the above.

If an impulse-momentum analysis is considered during the very short time of interaction, as shown in the picture, weight is a/an __________
A) impulsive force.
B) explosive force.
C) non-impulsive force.
D) internal force.

Over the short time span of a tennis ball hitting the racket during a player’s serve, the ball’s weight can be considered _____________
A) nonimpulsive.
B) impulsive.
C) not subject to Newton’s second law.
D) Both A and C.

A drill rod is used with a air hammer for making holes in hard rock so explosives can be placed in them. How many impulsive forces act on the drill rod during the drilling?
A) None B) One
C) Two D) Three

The 20 g bullet is fired horizontally at 1200 m/s into the 300 g block resting on a smooth surface. If the bullet becomes embedded in the block, what is the velocity of the block immediately after impact.
A) 1125 m/s B) 80 m/s
C) 1200 m/s D) 75 m/s

The 200-g baseball has a horizontal velocity of 30 m/s when it is struck by the bat, B, weighing 900-g, moving at 47 m/s. During the impact with the bat, how many impulses of importance are used to find the final velocity of the ball?
A) Zero B) One
C) Two D) Three

When the motion of one or both of the particles is at an angle to the line of impact, the impact is said to be ________
A) central impact. B) oblique impact.
C) major impact. D) None of the above.

2. The ratio of the restitution impulse to the deformation impulse is called _________
A) impulse ratio. B) restitution coefficient.
C) energy ratio. D) mechanical efficiency

occurs when the directions of motion of the two colliding particles are along the line of impact.

oblique impact

is the ratio of the particles’ relative separation velocity after impact, (vB)2 – (vA)2, to the particles’ relative approach velocity before impact, (vA)1 – (vB)1.

Two balls impact with a coefficient of restitution of 0.79. Can one of the balls leave the impact with a kinetic energy greater than before the impact?
A) Yes B) No
C) Impossible to tell D) Don’t pick this one!

2. Under what condition is the energy lost during a collision maximum?
A) e = 1.0 B) e = 0.0
C) e = -1.0 D) Collision is non-elastic.

Block B (1 kg) is moving on the smooth surface at 10 m/s when it squarely strikes block A (3 kg), which is at rest. If the velocity of block A after the collision is 4 m/s to the right, (vB)2 is
A) 2 m/s  B) 7 m/s 
C) 7 m/s  D) 2 m/s 

A particle strikes the smooth surface with a velocity of 30 m/s. If e = 0.8, (vx) 2 is _____ after the collision.
A) zero B) equal to (vx) 1
C) less than (vx) 1 D) greater than (vx) 1

Select the correct expression for the angular momentum of a particle about a point.
A) r × v B) r × (m v)
C) v × r D) (m v) × r

The sum of the moments of all external forces acting on a particle is equal to
A) angular momentum of the particle.
B) linear momentum of the particle.
C) time rate of change of angular momentum.
D) time rate of change of linear momentum.

If a particle moves in the x - y plane, its angular momentum vector is in the
A) x direction. B) y direction.
C) z direction. D) x - y direction.

If there are no external impulses acting on a particle

A) only linear momentum is conserved.
B) only angular momentum is conserved.
C) both linear momentum and angular momentum are conserved.
D) neither linear momentum nor angular momentum are conserved.

A ball is traveling on a smooth surface in a 3 ft radius circle with a speed of 6 ft/s. If the attached cord is pulled down with a constant speed of 2 ft/s, which of the following principles can be applied to solve for the velocity of the ball when r = 2 ft?
A) Conservation of energy
B) Conservation of angular momentum
C) Conservation of linear momentum
D) Conservation of mass

If a particle moves in the z - y plane, its angular momentum vector is in the
A) x direction. B) y direction.
C) z direction. D) z - y direction

If applicable, the method of instantaneous center can be used to determine the __________ of any point on a rigid body.
A) velocity B) acceleration
C) velocity and acceleration D) force

The velocity of any point on a rigid body is __________ to the relative position vector extending from the IC to the point.
A) always parallel B) always perpendicular
C) in the opposite direction D) in the same direction

When the velocities of two points on a body are equal in magnitude and parallel but in opposite directions, the IC is located at
A) infinity.
B) one of the two points.
C) the midpoint of the line connecting the two points.
D) None of the above.

When the direction of velocities of two points on a body are perpendicular to each other, the IC is located at
A) infinity.
B) one of the two points.
C) the midpoint of the line connecting the two points.
D) None of the above.

The wheel shown has a radius of 15 in and rotates clockwise at a rate of w = 3 rad/s. What is vB?
A) 5 in/s B) 15 in/s
C) 0 in/s D) 45 in/s

Point A on the rod has a velocity of 8 m/s to the right. Where is the IC for the rod?
A) Point A.
B) Point B.
C) Point C.
D) Point D.

If a rigid body is in translation only, the velocity at points A and B on the rigid body _______ .
A) are usually different
B) are always the same
C) depend on their position
D) depend on their relative position

If a rigid body is rotating with a constant angular velocity about a fixed axis, the velocity vector at point P is _______.
A) w x rp B) rp x w
C) drp/dt D) All of the above

Note, all points in a rigid body subjected to translation move with the

a disk is rotating at 4 rad/s. If it is subjected to a constant angular acceleration of 2 rad/s2, determine the acceleration at B.
A) (4 i + 32 j) ft/s2 B) (4 i - 32 j) ft/s2
C) (- 4 i + 32 j) ft/s2 D) (- 4 i -32 j) ft/s2

2. A Frisbee is thrown and curves to the right. It is experiencing
A) rectilinear translation. B) curvilinear translation.
C) pure rotation. D) general plane motion.

1. The fan blades suddenly experience an angular acceleration of 2 rad/s2. If the blades are rotating with an initial angular velocity of 4 rad/s, determine the speed of point P when the blades have turned 2 revolutions
(when w = 8.14 rad/s).
A) 14.2 ft/s B) 17.7 ft/s
C) 23.1 ft/s D) 26.7 ft/s

2. Determine the magnitude of the acceleration at P when the blades have turned the 2 revolutions.
A) 0 ft/s2 B) 3.5 ft/s2
C) 115.95 ft/s2 D) 116 ft/s2

1. A body subjected to general plane motion undergoes a/an
A) translation.
B) rotation.
C) simultaneous translation and rotation.
D) out-of-plane movement.

In general plane motion, if the rigid body is represented by a slab, the slab rotates
A) about an axis perpendicular to the plane.
B) about an axis parallel to the plane.
C) about an axis lying in the plane.
D) None of the above.

The position, s, is given as a function of angular position, q , as s = 10 sin 2q . The velocity, v, is

A) 20 cos 2q B) 20 sin 2q
C) 20 w cos 2q D) 20 w sin 2q

If s = 10 sin 2q , the acceleration, a, is

A) 20 a sin 2q B) 20 a cos 2q − 40 w2 sin 2q
C) 20 a cos 2q D) -40 a sin2 q

The sliders shown below are confined to move in the horizontal and vertical slots. If vA=10 m/s, determine the connecting bar’s angular velocity when  = 30.
A) 10 rad/s B) 10 rad/s
C) 8.7 rad/s D) 8.7 rad/s

If vA=10 m/s and aA=10 m/s, determine the angular acceleration, a, when  = 30.
A) 0 rad/s2 B) -50.2 rad/s2
C) -112 rad/s2 D) -183 rad/s2

When a relative-motion analysis involving two sets of coordinate axes is used, the x’ - y’ coordinate system will
A) be attached to the selected point for analysis.
B) rotate with the body.
C) not be allowed to translate with respect to the fixed frame.
D) None of the above.

In the relative velocity equation, vB/A is
A) the relative velocity of B with respect to A.
B) due to the rotational motion.
C) w × rB/A .
D) All of the above.

1. If the disk is moving with a velocity at point O of 15 ft/s and  = 2 rad/s, determine the velocity at A.
A) 0 ft/s B) 4 ft/s
C) 15 ft/s D) 11 ft/s

If the velocity at A is zero, then determine the angular velocity, . 2 ft. 15ft/s
A) 30 rad/s B) 0 rad/s
C) 7.5 rad/s D) 15 rad/s

Which equation could be used to find
the velocity of the center of the gear, C,
if the velocity vA is known?

A) vB = vA + wgear × rB/A B) vA = vC + wgear × rA/C
C) vB = vC + wgear × rC/B D) vA = vC + wgear × rC/A

If the bar’s velocity at A is 3 m/s, what “base” point (first term on the RHS of the velocity equation) would be best used to simplify finding the bar’s angular velocity when  = 60º?
A) A B) B
C) C D) No difference.