Physics Homework Memorize

Draw the problem out + label angle of inclination

How do you solve?

The integral of F from 0 —> 30 equals momentum. F grows linearly so area under curve = ½ bh = 660

Why did you miss this problem?

I calculated the momentum using total velocity instead of the x-component of momentum (force only applies force x-direction)

Why did you miss?

I calculated conservation of momentum before collision happened, but there is heat lost during collision. so, I should have calculated conservation immediately after the collision.

What is answer?

(5L)/9

What is answer?

(5/9) MR²

What is the answer?

(2/7)tan@

Moment of Inertia for Rod rotating about its center

(1/12)ML²

Moment of Inertia for rod rotating about its end

(1/3) mL²

Why did you miss this problem about energy of friction?

The energy of friction is only equal to the man-boat system bc rock does not touch water initially. only man-boat are slowed by friction.

Are energy and/or momentum conserved? A-B

No, neither are

Are momentum and/or energy conserved? D-E

Only energy is conserved

Why did you miss this?

the balls make right angle, so you can use pythagorean theorem to find the velocity component

How to solve the v of bullet and energy lost?

Momentum is conserved —> initial bullet momentum = spring block momentum + final bullet momentum. You find the velocity of the spring block with the potential energy of the spring (the spring expels its KE by returning to place after bullet exits). This potential energy of the spring = KE of the spring block.

Then, the initial energy (bullet KE) = KE of the spring block + KE of the bullet + energy lost.

Why did you get this problem wrong?

• the units

• KE = Us —> ½ (M +M) v² = ½ K x²

• x/sqrt(2) = the compression of each

What equation to solve?

How to find power?

Thrust = (rate of fuel)(velocity of exhaust) + (rate of air)(difference in velocity)

P = force x velocty

Force - Momentum Equations

Faverage = delta P / delta T

integral (F) dt = P

think of Newton’s cradle V1 = final V2 ((V1 becomes stationary)

downward

Why did you get this problem wrong?

I did not calc in radian units

Moment of Inertia of Thin Ring

½ M (R² + R²) = MR²

Why did you mess up I?

• I solved with diameter, not radius

Which is/are true?

I only

Why did you miss this problem?

The force on the pulley from the truck is half mgsin@ bc the T holds it at two parts

What is the equation for this problem? What is the shorthand equation maybe?

r = (width x g) / (height x w²)

Why did you get this problem wrong?

Once you find N, thats the horizontal force. You need a vertical force of Fg to get force of pin.

What is answer

T / sqrt2

Period of a Spring

How do you find angular frequency?

How to find amplitude?

Ignore the random info, it is still w = 2pi/T and T = 2pi sqrt(m/k)

Find v(t), then use A² = sin² + cos² and substitute values

When a spring is halved, what happens to K?

K doubles