IPC 4aCalculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving

toys, and machines;

On the left side: The formula is given in words

On the right side: The formula is given in symbols

Density = D = mass

volume

m

v

Formula Chart

Gravity

Constants, Symbols and

Units

Formulas

Power =Power = work work = = force x distanceforce x distance time timetime time

Newton’s 2Newton’s 2ndnd Law Law

TRIANGLE METHOD-

D = m/v

M

VD

An object has a density of 10 g/cm3 and a volume of 3 cm3. What is its mass?

XX

An object has a mass of 50 g and a volume of 10 cm3. What is its density?

An object has a mass of 50 g and a density of 5 g/cm3. What is its volume?

Answer: 30g

÷÷

Answer: 5g/cm3

Answer: 10cm3

Student Practice: Scrap Paper

TRIANGLE METHOD

f = ma

f

am

An object has a mass of 5g and an acceleration of 8 kg/s2 . What force does it exert?

XX

An object exerts a force of 100N and has a mass of 50 kg . What is its acceleration?

An object has a force of 200N and an acceleration of 2kg/ s2. What is its mass?

÷÷

Answer: 40N

Answer: 2kg/ s2

Answer: 100 kg

am

f

XX

÷÷

am

f

XX

÷÷

am

Student Practice: Scrap Paper

Triangle Method-Your Turn• Speed = distance/time (v=d/t)

• Power = work/time (p=w/t)

• Velocity of a wave=frequency x wavelength (v=fλ)

• Current = voltage/resistance (I = v/R)

t

d

v t P

w

t

v

f λ

v

I R

Student Practice: Scrap Paper

When solving a problem---• First read the problem carefully and

list what you know and what you are solving for.

• Second identify the formula from the formula chart that includes what you are given.

• Third Using the triangle method, set up the formula. You may have to rearrange the formula to solve for the unknown quantity.

Which formula?• The weight lifter used a force of 980 N to

raise the barbell 2.04 m over her head in 5.21 seconds. Approximately how much work did she do in raising the barbell?

• Approximately how much power did the weight lifter exert lifting the barbell in 5.21 seconds?

• What is the momentum of a 40 kg bike riders moving at 45 km/h?

• What is the mass of a 500.00 mL sample of seawater with a density of 1.025 g/mL?

Work = force x distance

Power = Work/time

Density = mass/volume

Momentum = mass x velocity

Which of the following weightlifters does themost work on a 100-pound barbell when

liftingthe barbell over his or her head?A. A weightlifter who is 5 feet 8 inches tallB. A weightlifter who is 6 feet 0 inches tallC. A weightlifter who is 6 feet 2 inches tallD. A weightlifter who is 6 feet 4 inches tallFrom formula chart

Force

Distance

Which of the following changes would notincrease power? A. A decrease in the time it takes to do

work.B. A decrease in the distance over which a

force is appliedC. An increase in the force appliedD. An increase in the work added

Power = work = force x distance time time

From formula chart

To decrease power then work must decrease or time increase.

To decrease work you must decrease the force or decrease the distance

When solving a problem---• First read the problem carefully and

list what you know and what you are solving for.

• Second identify the formula from the formula chart that includes what you are given.

• Third Using the triangle method, set up the formula. You may have to rearrange the formula to solve for the unknown quantity.

WHAT FORMULA??

• Get out your white board and a dry erase marker

• We will play a game called “What Formula”

• When you are shown the problem, look at your formula chart and select the formula you would use to solve the problem

• Write the formula on your white board and turn it so your teacher can see it. (You DON’T need to solve the problem)

What Formula?

V = d/t

Speed = distance

traveled/time

What Formula?

P=w/t

Power = work/time

What Formula?

KE = mv2/2

Kinetic Energy = ½

(mass x velocity2)

What Formula?

p = m x a

Momentum = mass x

acceleration

What Formula?

V = d/t

Speed = distance

traveled/time

What Formula?

F = m/a

Force = mass/

acceleration

What Formula?a = vf-vi/∆t

Acceleration = final

velocity – initial

velocity/ change in

time

What Formula?

V = d/t

Speed = distance

traveled/time

What Formula?

P=w/t

Power = work/time

What Formula?

F = m/a

Force = mass/

acceleration

What Formula?a = vf-vi/∆t

Acceleration = final

velocity – initial

velocity/ change in

time

What Formula?

V = d/t

Speed = distance

traveled/time

Density Foldable

We will now make a Density

foldable

Density Foldable

DENSITY

FORMULA

UNITS

SAMPLE PROBLEMS & SOLUTIONS

g=g/cm3 x cm3

g/cm3=g/cm3

Cm3=g/g/cm3

m=D x v

D=m/v

V=m/D

Inside Foldable

Definition Under FlapDensity is the amount of mass in a given

volume

D=m/v; v=m/D; m=D x v

FORMULA

UNITS

SAMPLE PROBLEMS

GOOD LUCK!!!!