Review: Forces, Systems, and Tension

Review: Forces, Systems, and Tension

Concepts, Problem Analysis, and Solving for Tension

In this lesson, you will:

• Analyze FBD's with balanced and unbalanced forces

• Determine Mass of System

• Determine Net Force on System

• Determine Net Acceleration of System

• Use these values to determine individual effects on each entity in the system (cart vs. block vs. hanging mass etc.)

Force types

Make sure you understand which forces are present in particular objects

Multiple Select

Neglecting drag, which forces are present on the hanging mass?

(Check all that apply.)

• Gravity/Weight

• Friction

• Tension

• Thrust

Multiple Select

Neglecting drag and friction, which forces are present on the cart?

(Check all that apply.)

• Gravity/Weight

• Friction

• Tension

• Normal

Types of Forces on Hanging Mass

• Gravity (as always!)

• Tension (because it's hanging by SOMETHING)

• If drag is neglected, that's all.

• Just pay attention to what it is connected to...

Types of Forces on a Truck or Pulled Trailer

• Gravity (as always!)

• Tension (because it's pulling/being pulled by SOMETHING) --> Horizontal here

• Drag (unless omitted)

• NORMAL Force...this object is contacting a surface

• Friction (unless omitted)

• Is it connected to something else?

Types of Forces on Rocket/Helicopter/Lifted Load

• Gravity (as always!)

• Tension (because it's pulling/being pulled by SOMETHING) --> VERTICAL here

• Drag (unless omitted)

• Is it connected to something else?

Multiple Select

What forces act on the rising helicopter?

(Check all that apply.)

• Gravity/Weight

• Drag

• Tension

• Friction

• Thrust

Multiple Select

What forces act on the rising load?

(Check all that apply.)

• Gravity/Weight

• Drag

• Tension

• Friction

• Thrust

Mass of the system

• Just look at all the masses present

• Find the sum!

Fill in the Blank

Find the mass of the system:

Multiple Select

Due to the masses hanging, which direction will the blocks go?

(Check 2 boxes.)

• Left down

• Right down

• Left up

• Right up

Fill in the Blank

Find the NET FORCE on the System:

(Use 10 m/s/s for acceleration due to gravity.)

Fill in the Blank

Find the magnitude (number) for the NET ACCELERATION of the system:

(Use 10 m/s/s for gravity accel.)

Open Ended

Find the force of tension present in the cable connecting the masses.

To the nearest whole number:

Mass of the System

• Truck = 3000 kg

• Trailer = 1200 kg

• System Mass = ?

Fill in the Blank

What is the Net Force (in N) on the System in the FBD presented?

Fill in the Blank

Using the 3150 N net force, what is the net acceleration of the system (in m/s/s)?

Open Ended

Determine the force due to Tension in the tow cable.

One more scenario

• Friction applies now

•  $F_f=\mu\cdot F_n$  

Multiple Select

What forces are acting on the sliding block? (Omit drag.)

Check all that apply.

• Gravity/Weight

• Friction

• Tension

• Normal
  

• Thrust

Multiple Select

What forces are acting on the hanging block? (Omit drag.)

Check all that apply.

• Gravity/Weight

• Friction

• Tension

• Normal
  

• Thrust

Multiple Choice

What object will cause a net force in this FBD?

• The block on the table

• The hanging block

• Both blocks

• Neither, it's balanced

Fill in the Blank

Given a kinetic coefficient of 0.2, what is the force due to friction in this FBD?

(Use 10 for g.)

Fill in the Blank

With a force due to friction of 18N, what is the NET FORCE on the SYSTEM?

(Use 10 for g.)

Fill in the Blank

What is the acceleration (vector) of the hanging block?

(Use 10 for g, round answer to nearest tenth.)

Open Ended

Determine the force due to Tension in the cable.

(Use 10 for g, round answer to nearest tenth.)