Principles of Technology 2 Unit 8 Test

The law of conservation of momentum tells us that in an isolated system _________________________.

• the total momentum before an interaction equal!s the total momentum after the interaction

• the velocity before an interaction equals the velocity after the interaction

• the kinetic energy before an interaction equals the kinetic energy after the interaction

• the total momentum before an interaction is greater than the total momentum after the interaction

An object's momentum tells us mostly about ___________________.

• the potential energy the object has

• the amount of motion the object has

• the physical size of the object

• the specific gravity of the object

 $L_{mom_{ }}=\$ 

•  $I\omega$  

•  $mI$  

•  $m\ +\ i$  

•  $mr^2$  

Which of the following will give you the full and correct information about a rotating object's angular momentum?

• mass and angular velocity

• moment of inertia and angular velocity

• mass and radius

• linear momentum and specific gravity

When balancing an automobile wheel that is mounted on the automobile, a 30-lb tangential force is applied to the tread of the tire for 15 seconds. The tire and wheel have a radius of 1.5 feet. The angular impulse of the wheel is ______________. (Hint: Use the equation,  $Ang\ Imp\ =\ T\Delta t$  where  $T\ =\ F\ x\ r$  to complete the sentence.

• 3 (lb·ft)·sec 

• 300 (lb·ft)·sec

• 450 (lb·ft)·sec

• 675 (lb·ft)·sec

A steam turbine has blades of 0.6-m radius. Steam strikes the turbine blade tips with a force of 1600 N. If the steam is directed onto the turbine blade tips for 60 seconds, what is the angular impulse given to the turbine?

• 16 (N·m)·sec

• Good Luck!

• 960 (N·m)·sec

• 159,960 (N-m)·sec

A constant force of 1500-lb brings a truck to a stop in 30 seconds on a straight road. The truck experiences a change in velocity of 80 ft/sec during the time the force is applied. Find the mass of the truck. (Hint: Use the relationship $F\Delta t\ =\ m\Delta v$  .)

• 562.5 kg

• 562.5 slugs

• 3,600,000 kg 

• 3,600,000 slugs