Honors Physics

Good Morning! Please…

Take out your vocabulary and hand them in to the bin in the front of the room (make sure your name is on it)

Work on the warm-up problem: Convert the following so that they are expressed as a

digit between 1-999, using a prefix. 0.0035 Volts 2.5x105 grams

Housekeeping…

**Notice** the homework assignment due Tuesday has changed Different problems from the text than were

originally assigned. Lab not due on Monday (probably due

Wednesday)

Homework Solutions:

4. a) 105 km/hr b) 29 m/s

c) 95 ft/sec 5. a) 203 miles

b) 61 miles/hr 7. a) 4.29 m/s

b) 0 m/s 9. 2.7 min

Homework Problem #5 You are driving home from school steadily at 65 miles/hour

for 130 miles. It then begins to rain and you slow to 55 mph. You arrive home after driving 3 hours and 20 minutes. (a) how far is your hometown from school? (b) What was your average speed?

Steps for solving: Draw and write out the information given Identify unknown values Identify equations to use Hint: break the problem into two trip segments

The RATE of CHANGE of VELOCITY

Change = FINAL - INITIAL

v = Final velocity – Initial velocity

2///seconds

ondmeters/secsmorssm

t

va

Acceleration – The Definition

A Cessna Aircraft goes from 0 m/s to 60 m/s in 13 seconds. Calculate the aircraft’s acceleration.

13

060

t

va 4.62 m/s/s

Example

Example: The Cessna now decides to land and goes from 60 m/s to 0 m/s in 11 s. Calculate the Cessna’s ?acceleration

11

600

t

va - 5.45 m/s/s

Example

Constant Velocity Car Lab

Table & graphs should be completed on a separate piece of graph paper with ruler

Find average time Find change in time: time it took for car to

travel each of the 0.2 m length segments Ex: time to go from 0.0m to 0.2m, time to go from

0.2m to 0.4m, etc. Instantaneous velocity = 0.2 m ÷ average time for length

segment

Problem-Solving Techniques1. Read & re-read the whole problem carefully.

2. Draw a diagram or picture of the situation. Include coordinate axes: usually use x-axis to the right as positive, x

axis to the left as negative.

3. Write down the “known” and “unknown” quantities

4. Think about the physics principles that apply

5. Consider which equations relate the quantities involved. Make sure the equation is valid to use for that problem You may need to use a series of equations to solve the problem – not

just one.

6. Carry out the calculations. Round at the end of the calculation only.

7. Review the problem: is it a reasonable solution?

8. Do a check of work by checking units: dimensional analysis