Physics

Question 1

Tips

Answer 1

• look at units and answer choices

- eliminate pos vs neg

Question 2

Rate of change

Answer 2

-Final minus initial divided by total time

Rate of change example:
Dosage increased uniformly 5 mg/hr to 20 mg/hr over 10 hours. Rate of change = 20-5/10 = 1.5 mg/hr^2
Then do dimensional analysis

Question 3

Change in electric potential energy

Answer 3

U = q deltaV

ex) Na/K pump putting a Na+ out
- must be positive PE since going against conc. gradient
- gave -70 mV (turn to V) and know that a positive charge is 1.6 x 10^-19 C

V = J/C

Question 4

Temperatures

Answer 4

0 C warmer than 0 F warmer than 0 K

0 K = absolute 0 = coldest

0 degrees C = 32 degrees F

Question 5

Know temperature reference points

Answer 5

0 K = -273 C = -460 F

0 C = 32 F = 273 K

100 C = 212 F = 373 K

Question 6

Lowering a book

Answer 6

Book is 1 kg, lower 1.8 to 1 m

W = mgh (hf - hi makes it neg) = 110-0.8 = -8 J

Direction of book goes down while force is up so W is negative

Question 7

Intensity

Answer 7

I = P / A = Watts/m^2
P = W / t = J/s

If P = 0.01 J/s, SA = 60 mm^2, convert to m^2 and divide

Question 8

Resistance

Answer 8

R=density*L/A

2d = 2r = 4A = 1/4 R

Question 9

Electric Fields and Capacitors

Answer 9

E = V/d

A circuit has a R, battery/V, and capacitor
How increase electric field of capacitor? How decrease?

Adding battery increases V drop across resistor and increase electric field as E = V/d

Adding a resistor in series to capacitor in series decreases voltage drop across capacitor = E decreases

Adding a resistor in parallel does not affect voltage drop across capacitor

Increasing the distances between the plates decreases the electric field

Question 10

Torque

Answer 10

Fdsin(theta)

Question 11

Kick a ball into a goal

Answer 11

20 ft away, takes 2 seconds, kick at 60 degrees from the ground
Vox = dx/t = 10 m/s
Vox = Vocos60

Question 12

Run parallel 3 m/s, 6 m apart

Answer 12

t = 2 sec
Vo of ball?

3 m/s x 2 s = 6 m traveled, and 6 m apart = hypotenuse is 6*sqrt(2)
^divide by 2 sec (d/t) to get velocity

Question 13

Kick 2 balls

Answer 13

Kick 400g soccer ball at 30 degrees, Vo = 12 m/s
Kick 450g soccer ball at 60 degrees, Vo = 6 m/s
Faster to reach ground?

The one with a smaller vertical velocity will reach the ground faster. Horiz vel is irrelevant

Vy = Vosintheta
Vy 400g = 12 sin 30 = 6 m/s
Vy 450g = 6 sin 60 = 3 root 3 = 3 * 1.7 which is < 6 m/s

450 g ball returns to the ground first