Homework Due

Read & Study Ch 11; Ch 11 vocab

Tonight’s HW

Read & Study 11.1 - 11.4 – Do #1- 12 p. 165

Do Now Take a POGIL; put asideGrab a clicker and get ready for your Ch 11 pre assessment!

Chapter 11, Lesson 1: April 15 & 16, 2013

Suppose you try to push open the door below 3 times. First, you push by the HINGE (see then ‘x’). Then, you push in the middle.

Finally, you push by the handle. WHICH IS EASIEST? 

1 2 3

0% 0%0%

1. 2. 3.

Can the same torque be exerted from different forces?

1 2 3

0% 0%0%

1. YES2. NO3. IMPOSSIBLE TO SAY

If you cannot exert enough torque to turn a stubborn bolt, would more torque be produced if you fastened a length of rope to the

wrench handle as shown?

1 2 3

0% 0%0%

1. YES2. NO3. IMPOSSIBLE TO SAY

If an object has a LARGE ROTATIONAL INERTIA, do you think it is easy or difficult to get it to rotate?

1 2 3

0% 0%0%

1. EASY2. DIFFICULT 3. IMPOSSIBLE TO SAY

You roll a hollow disk and a solid disk down the same ramp. You start them from the same height at the

same time. Which reaches the bottom first?

1 2 3

0% 0%0%

1. Solid disk2. Hollow disk3. Not enough

information to say

The 3 batons below have the SAME mass, but the mass is distributed differently. The 1st baton has most of the mass close to the handle. The 2nd baton has most of the mass far from the handle. The 3rd baton has the mass evenly distributed from the handle.Which is easiest to balance?

1 2 3

0% 0%0%

1. 2. 3.

On to the POGIL!

• CHECK IN AT STOP SIGNS!• We are NOT going over as a class – PLEASE

check in with a teacher as a group! • Stopping with AT LEAST 10 minutes

left for a clicker exit!!! • If you work efficiently, we may have time to

give back your quizzes today…if not, next class

Suppose you try to push open the door below 3 times. First, you push by the HINGE (see then ‘x’). Then, you push in the middle.

Finally, you push by the handle. WHICH IS EASIEST? 

1 2 3

0% 0%0%

1. 2. 3.

Door 3 – bigger lever arm, so you can push with less force and still get the same torque!

Countdown

10

Can the same torque be exerted from different forces?

1 2 3

0% 0%0%

1. YES2. NO3. IMPOSSIBLE TO SAY

F   x    LA      = Torque =      F    x    LA

Countdown

10

If you cannot exert enough torque to turn a stubborn bolt, would more torque be produced if you fastened a length of rope to the

wrench handle as shown?

1 2 3

0% 0%0%

1. YES2. NO3. IMPOSSIBLE TO SAY The rope doesn’t change the lever arm!  You need a stronger person (more force), or a bigger wrench (bigger lever arm)! Countdown

10

If an object has a LARGE ROTATIONAL INERTIA, do you think it is easy or difficult to get it to rotate?

1 2 3

0% 0%0%

1. EASY2. DIFFICULT 3. IMPOSSIBLE TO SAY

More R.I., more RESISTANT to change in rotation!  If it’s at rest, it REALLY wants to stay at rest!  If it’s rotating, it REALLY wants to keep rotating!  

Countdown

10

The 3 batons below have the SAME mass, but the mass is distributed differently. The 1st baton has most of the mass close to the handle. The 2nd baton has most of the mass far from the handle. The 3rd baton has the mass evenly distributed from the handle. Which has the GREATEST rotational inertia?

1 2 3

0% 0%0%

1. 2. 3.

The farther the bulk of the mass is from the turning axis, the MORE R.I. there is!!!

Countdown

10