Flashcards in Physics Things to Know Deck (30):

1

## How do you determine instantaneous velocity from a position-time graph?

### Slope at a given time

2

## How do you determine instantaneous velocity from a velocity-time graph?

### Value at the given time

3

## A block is in equilibrium. What is the Newton's third law force pair to the normal force?

### The force the block puts on the surface

4

## What is the same for resistors in parallel?

### Voltage drop

5

## What is the equivalent resistance of two 50 ohm resistors in parallel?

### 25 ohms

6

## What is the more common word for the "magnitude of the velocity vector?"

### Speed

7

## Write the impulse-momentum theorem.

### FΔt = Δp

8

## State the formula for the angular momentum of a point object.

### L = mrv

9

## State the formula for the angular momentum of an extended object, like a disk or a sphere.

### L = Iω

10

## A 1 kg object moves at 2 m/s. Can this object collide and experience MORE that 2 N᛫s of impulse?

### Yes

11

## What property of a circuit involved the number of electrons passing a position in 1 s?

### Current

12

## John exerts a 4 N force to the left on a cart; Peggy exerts a 3 N force to the right on the cart. Which way is the cart moving?

### Can't be determined

13

## What physical property of a wave relates to the energy carried by the wave?

### Amplitude

14

## Under what conditions can you set up forces equal to down forces?

### Equilibrium (a = 0)

15

## Equation for energy stored by a spring.

### PE = 1/2 kx²

16

## A 1 kg wooden crate and a 2 kg wooden crate are separately dragged across the floor. What quantity must be the same for both crates?

### Friction (μ)

17

## Write the equation for the electrical force between two point charges.

### F = (kq1q2) / r²

18

## Two massive objects each have a net negative charge. When they are placed near one another, do they attract or repel electrostatically?

### Repel

19

## Write the equation for the period of a pendulum.

### T = 2π √(l/g)

20

## Write two versions of the equation for electrical power.

###
P = IV

P = I²R

P = V² / R

21

## Wire 1 is 20 cm long and made out of aluminum. Wire 2 is 40 cm long, of the same cross sectional area, and also made out of aluminum. How many times larger is the resistivity of wire 2 compared to wire 1?

### Resistivity is the same.

22

## The amplitude of an antinode on a standing wave on a string is 2 cm; the period of the wave is 4 s. What is the average speed of the string at the position of the antinode?

### 2 cm/s

23

## Draw a representation of the longest-wavelength standing wave that can exist in a pipe which is open at one end and closed at the other end.

### Half a wave

24

## A planet's orbit about a sun is elliptical. Consider a system consisting of just the planet. Is the planet's angular momentum about the sun conserved?

### No

25

## An object is hung from a spring scale, which reads 2.0 N. Dividing by 10, it's determined that the object's mass is 0.2 kg. Which kind of mass was determined?

### Gravitational Mass

26

## An object is attached to a horizontal spring, compressing the spring by 0.15 m. A second object, twice as massive as the first, compressed the same spring by 0.15 m. By how much has the potential energy of the spring-object system changed?

###
None

(1/2kx²)

27

## A 10 N block is on a surface is which the static friction coefficient is 0.2. The force of friction on the block is 1 N. How is this possible?

### F (static friction) ≤ μ (static) F (normal)

28

## Identify the error: "Ball A was thrown at a speed of 30 m/s at an angle of 20° above the horizontal. Since its acceleration is 10 m/s², its speed after 3 s will be zero."

### Acceleration is in the vertical direction. Only Ball A will have a non-zero speed.

29

## Why is it wrong to say "the kinetic energy of the hanging block is downward?"

### Energy is secular with no direction

30