Chem/Phys Deck 6: Work, Energy, Springs, Optics & Waves

What is the equation for work?

W=Fdcosθ

When is work positive?

When force and displacement are in the same direction

When is work negative?

When force opposes displacement.

If the force is perpendicular to motion, how much work is done?

Zero

What is kinetic energy?

KE=1/2​mv^2

What is gravitational potential energy?

PE=mgh

What is elastic potential energy?

PE=1/2kx2

In a closed system, what is conserved?

Mechanical energy

What happens to potential energy as an object falls?

Potential energy decreases while kinetic energy increases

What is power?

P=W/t

Power is the rate of doing work.

SI unit of power?

Watt (W)

1 W = 1 J/s

What is Hooke's Law?

F=−kx

What does the negative sign in Hooke's Law mean?

The spring force always acts opposite the displacement

If the spring constant doubles, what happens to the force for the same stretch?

The force doubles

What is mechanical advantage?

MA=Output Force​/Input Force

Which simple machine decreases the amount of force needed?

Any machine with a mechanical advantage greater than 1

What equation relates wave speed, frequency, and wavelength?

v=fλ

If frequency increases while wave speed stays constant, what happens to wavelength?

Wavelength decreases

Which has the highest frequency in the electromagnetic spectrum?

Gamma rays

Which has the longest wavelength?

Radio waves

What equation relates focal length and lens curvature?

1/f​=1/o​+ 1/i​

• f = focal length

• o = object distance

  • i = image distance

A converging lens is also called what?

A convex lens

A diverging lens is also called what?

A concave lens

Which lens can produce a real image?

Convex

Which lens always produces a virtual image?

Concave

A concave mirror can produce what types of images?

Real or virtual, depending on object position

A convex mirror always produces what type of image?

Virtual, upright, and smaller.

What is Snell's Law?

n1​sinθ1​=n2​sinθ2​

Light entering a medium with a higher refractive index bends...

Toward the normal.

Light entering a medium with a lower refractive index bends...

Away from the normal

What determines the pitch of a sound?

Frequency

What determines loudness?

Amplitude

What is the half-life?

The time required for half of a radioactive sample to decay.

After two half-lives, what fraction of the original sample remains?

1/4

After three half-lives?

1/8

Which equation should immediately make you think "energy"?

• KE=1/2​mv2

• PE=mgh

• PE=1/2kx²

What is the speed of light?

3.0×10^8 m/s

What is the elementary charge?

1.6×10^−19 C