while moving

Quiz 1 - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

while moving

Mass (m) = kilograms, kgDistance (s) = meters, mTime (t) = seconds, s

Weight = m*g (Newtons)

Quiz 1 Makeup - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

Weight = m*g (Newtons)

Mass (m) = kilograms, kg1Mg = 1000 kgDistance (s) = meters, mTime (t) = seconds, s

Quiz 2 - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

Weight = m*g (lb)Mass (m) = kilograms, mass (m) = kgDistance (s) = meters, mTime (t) = seconds, s

Weight = m*g (Newtons)

Mass (m) = slugsDistance (s) = ftTime (t) = seconds, s

14-68 The 50 lb block rests on a rough surface for which the coefficient of kinetic friction is μk = 0.2. A force of 60 lb acts on the block in the direction shown. If the spring is originally un-stretched and the block is at rest, determine the power (in hp) developed by the force at the instant the block has move 1.5 ft.

Quiz 3 - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

Weight = m*g (lb)

Mass (m) = slugsDistance (s) = ftTime (t) = seconds, s

Mass (m) = kgDistance (s) = mTime (t) = seconds, s

Weight = m*g (N)

Spring

Gear ratio

The spring has a stiffness of 200N/m. The mass of the block is 25 kg. The unstretched length of the spring is 0.2m. The coefficient of kinetic friction is 0.1. Find the acceleration of the block at the instant shown.

0.4m

0.3m

Midterm Test - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

Most credit is given for developing the equations with all known values. Leave the algebra until last.

2. The smooth block B, having a mass of 0.2 kg, is attached to the vertex A of the right circular cone using a light cord. If the block has a constant speed of 0.5 m/s around the cone, determine the tension in the cord and the reaction which the cone exerts on the block.

Midterm Test - Dynamics – Fall 2010

3. The drop hammer (H) has a weight of 900 lb and falls from rest at h = 3 ft onto a forged anvil plate (P) that has a weight of 500 lb. Neglect friction in all guide posts.a) Find the velocity of the hammer just before it strikes the anvil. b) The coefficient of restitution is 0.6. Find the velocity of the plate after the collision.

Most credit is given for developing the equations with all known values. Leave the algebra until last.

Midterm Test - Dynamics – Fall 2010

3 c) If the plate in the previous problem leaves the collision at 14.3 ft/s downward, what is the maximum compression of the springs? The springs have a combined stiffness of 500 lb/ft.(note: the springs are originally compressed by the weight of the plate)

4. For a short period of time, the motor turns gear A with a constant angular acceleration of αA = 4.5 rad/s2, starting from rest, lifting the cylinder. a) Find the angular acceleration of gear B. b) Find the linear acceleration of the cylinder. The cord is wrapped around pulley D which is rigidly attached to gear B. c) If the motor and gear train are 90% efficient, find the power output of the motor at 3 seconds. The mass of the cylinder is 10 kg.

Midterm Test - Dynamics – Fall 2010

From velocity analysis ωAB = - 2.309 rad/s

Quiz 4 - Dynamics – Fall 2010 Name _________________________________Calculator in degrees!

From velocity analysis ωAB = - 2.309 rad/s

Quiz 4 - Dynamics – Fall 2010 Name _________________________________

Quiz 5 - Dynamics – Fall 2010 Name _________________________________

The spool has a mass of 8 kg and a radius of gyration of kG = 0.35m. Find the tension in the supporting cord starting from rest.

Quiz 6 - Dynamics – Fall 2010 Name _________________________________

Note: brackets not 1.5 m apart. Sketch positions 1 and 2 carefully

Quiz 7 - Dynamics – Fall 2010 Name _________________________________

1 (24pts) A uniform 50 kg crate rests on a horizontal surface for which the coefficient of kinetic friction is μk = 0.2. Will the crate slip or tip with the 600 N force? (must solve algebra to answer question)

Exam - Dynamics – Fall 2010 Name _________________________________

2 (26pts) The assembly consists of two 15 lb slender rods and a 20 lb disk. If the spring is un-stretched and the assembly is at rest in the position shown, find the angular velocity of rod AB at the instant θ = 00. The disk rolls without slipping. (use work and energy)

Exam - Dynamics – Fall 2010

3 (24 pts) A uniform rod having a weight of 10 lb is pin supported at A from a roller which rides on a horizontal track. If the rod is originally at rest, and a horizontal force of F = 15 lb is applied to the roller, determine the acceleration of the roller. Neglect the mass of the roller and the size d in the computations.

Exam - Dynamics – Fall 2010

4 (14 pts) The spring shown stretched 6 in when it is loaded with a 50 lb weight. Determine the equation which describes the position of the weight as a function of time if the weight is pulled 4 in below its equilibrium position and released from rest at t = 0.Let up be positive.

t

Exam - Dynamics – Fall 2010

5 (12 pts) For the system shown, write the equation for the steady-state motion (x as a function of time).

20kg

F = 90sin 6t

Exam - Dynamics – Fall 2010

ωn=√ km=√ 80020

=6.325

cc=2mωn=2 (20 ) (6.325 )=253c <? cc 125 < 253 system vibrates

xP=X' sin(ω0t−φ

')

F0

k= 90

800=0.1125

ω0

ωn= 6

6.325=0.9486

ccc

=125253

=0.4941

X '=F0/k

√ [1−(ω0/ωn )2 ]2+[2 (c /cc ) (ω0/ωn ) ]2= 0.1125

√[1−(0.9486 )2 ]2+[2 (0.4941 ) (0.9486 ) ]2

X '=¿0.1193

φ '=tan−1 ⌊2¿¿

φ '=¿1.464 rad

xP=X' sin(ω0t−φ

')=0.1193sin(6 t−1.464)

0.01003 0.8787

0.1002