**40 N**

**30**

0

What does the coefficient of static friction need to be to keep it in place?

**15 Kg**

**O**

= ?

**How steep can I tilt the board before the block slides.**

Assume coefficient of static friction is .36

Assume coefficient of static friction is .36

**At this angle, say it is 'bumped' and starts sliding, let the coefficient of kinetic friction be .25, what is the acceleration?**

**5 kg**

**10 kg**

**What coefficient of static friction is needed to keep it from sliding.**

**let the coefficient of kinetic friction be .35 what is the tension and the acceleration?**

**F =?**

**u = .25**

**7 kg**

**5 kg**

**20 kg**

**The orange block with a coefficient of friction of .25 is found to reach a speed of 2 m/s after a distance of 1.5 m, what force is needed if the two boxes are frictionless?**

F

F

F

F

P

fr

G

N

F

F

F

fr

G

N

F

F

F

T

fr

G

N

F

T

G

F

F

F

T

fr

G

N

F

F

F

T

G

N

v = 3.83 m/s

T = 14.7 N

**20 kg**

**10 kg**

If I hold the 20 kg mass, what is the tension?

How do the accelerations of the two objects relate.?

If released with no friction, what is the acceleration of the triangle?

1.09 m/s^2

49 N

a=2 a

x

y

What is the tension in the string now?

43.6 N

**60 kg**

**What is the tension in the rope?**

"I have a question about the elevator scale problem. "

A 55.0 kg students is in an elevator and pushes the button to go up. Briefly the acceleration is 0.300 g as it starts moving up. If she is standing on a scale what would it read while this acceleration is happening? (answer should look like '75.2 kg' )

1 picture

2 FBD ( 2 forces......)

3 F=ma

4 Newtons 3rd law ( Fn = Scale)