4*6 Forces Acting During Acceleration: Apparent Weight on a Roller Coaster WDYS??? (p406) . WDYT??? Your weight (does/does not) change when you are riding a roller coaster. If you were sitting on a scale, it (would/would not) give different readings at different places on the roller coaster.

4*6 NOTES: (p410-415) Forces Acting During Acceleration Using Newton’s 1st and 2nd Law to Explain Forces Acting During Constant Speed and Acceleration Newton’s 1st Law = Inertia Newton’s 2nd Law  a = F/m F = m×a m = F/a Constant velocity = Zero acceleration = NO Fnet Balanced = NO movement OR at a constant speed Unbalanced = movement where the vector is longer and the magnitude (#N) is larger

A. At constant speed Constant Speed UP = Constant Speed DOWN = SAME scale reading = Fweight = FN

B. Positive acceleration Acceleration UP = LARGER scale reading = FN is GREATER than Fweight

c. Negative Acceleration Acceleration DOWN = SMALLER scale reading = FN is LESS than Fweight

Force = m × a, its units are Newtons (N) 2. Calculating Acceleration Force = m × a, its units are Newtons (N) Weight = m × g, its units are Newtons (N) Therefore, Force = Weight Free Fall (broken elevator cable)  the scale would NOT push up at all and the reading would be ZERO

4*6 Physics Talk: (p414) Forces Acting During Acceleration 3. Apparent Weight Normal Force (FN) = Apparent Weight (FN) = (m × g) + (m × a) Acceleration UP = MORE Contact Force = LARGER “Apparent” Weight = You feel like you weigh MORE!!! Acceleration DOWN = LESS Contact Force = SMALLER “Apparent” Weight = You feel like you weigh LESS!!! Apparent Weight = (m × g) + (m × a)

Sample Problems (model) A man with a mass of 50kg is on an elevator, the elevator is accelerating at +2 m/s/s. What is his apparent weight?

Sample Problems (team) A woman with a mass of 25kg is on an roller coaster, the ride is accelerating at -2 m/s/s. What is her apparent weight?

Sample Problems (you) A kid with a mass of 15 kg is on an elevator, the elevator is accelerating at 3 m/s/s. What is his apparent weight?

Free Fall  the ONLY force acting on an object is GRAVITY; (Fweight) 4. Air Resistance Free Fall  the ONLY force acting on an object is GRAVITY; (Fweight) Acceleration due to GRAVITY is IDENTICAL for ALL objects falling on Earth…10m/s/s!!!!! Air Resistance  the force working AGAINST GRAVITY that pushes upward on falling objects; (FN) ***4-6 Cu/PTG***

4*6 TOTD No movement and constant speed are two examples of __________ forces. On a free-body diagram, if there is no movement or its at constant speed, then the arrow/forces = _____. _____ is the unit for both Force and Weight. One feels _____ when they are moving DOWN in an elevator because they have _____ contact force. The equation for Apparent Weight = __________.

BOOKWORK 4-6 CU (p 415 #1-5; write questions) 4-6 PTG (p. 418, #1-8 skip 4)