Physics Problems for 10-7-16

 

Problem 1

What is the approximate diameter of an inflated basketball?
(1) 2 × 10–2 m
(2) 2 × 10–1 m
(3) 2 × 100 m
(4) 2 × 101 m

¿Cuánto es el diámetro aproximado de un balón de básquet inflado?
(1) 2 x 10–2 m
(2) 2 x 10–1 m
(3) 2 x 100 m
(4) 2 x 101 m

Discussion and Solution:
This type of problem is meant to determine if you have any concept of length using metric units of measure, not English units.
Choice (1) is about one inch (2 x 10-2 m = 2 cm ≈ 1 in.)
Choice (2) is about 10 inches.
Choice (3) is 2 meters (≈ 6 ft).
Choice (4) is 20 meters (≈ 60 ft).

Problem 2

A 75-kilogram hockey player is skating across the ice at a speed of 6.0 meters per second. What is the magnitude of the average force required to stop the player in 0.65 second?
(1) 120 N
(2) 290 N
(3) 690 N
(4) 920 N

Un jugador de hockey de 75 kilogramos está patinando por el hielo a una rapidez de t, 6.0 metros sobre segundo. ¿Cuál es la magnitud de la fuerza promedio requerida para detener al jugador en 0.65 segundo?
(1) 120 N
(2) 290 N
(3) 690 N
(4) 920 N

Discussion and Solution:
F = ma, where F = force, m = mass, and a = acceleration.
a = Δv/t, where a = acceleration, Δv = change in velocity and t = time.
Δv = (vfvi), where Δv = change in velocity, vf = final velocity, and vi = initial velocity.
Combining these three equations together, we get:

F = m(vfvi)/t

Substituting in what we know, we get:

F = m(vfvi)/t = (75 kg)(0.0 m/s – 6.0 m/s)/(0.65 s) = 692.3 N

Choice (3).

Problem 3

Astronauts traveling toward Earth in a fast moving spacecraft receive a radio signal from an antenna on Earth. Compared to the frequency and wavelength of the radio signal emitted from the antenna, the radio signal received by the astronauts has a
(1) lower frequency and a shorter wavelength
(2) lower frequency and a longer wavelength
(3) higher frequency and a shorter wavelength
(4) higher frequency and a longer wavelength

Astronautas viajando hacia la Tierra en una rápida nave espacial reciben una señal de radio de una antena en la Tierra. Comparado a la frecuencia y la longitud de onda de la señal de radio emitida desde la antena, la señal de radio recibida por los astronautas tiene una
(1) menor frecuencia y una longitud de onda más corta
(2) menor frecuencia y una longitud de onda más larga
(3) mayor frecuencia y una longitud de onda más corta
(4) mayor frecuencia y una longitud de onda más larga

Discussion and Solution:
Use the Doppler Effect to answer this question.
Choice (3).

Problem 4

On the atomic level, energy and matter exhibit the characteristics of
(1) particles, only
(2) waves, only
(3) neither particles nor waves
(4) both particles and waves

En el nivel atómico, la energía y la materia exhiben la características de
(1) partículas, solamente
(2) ondas, solamente
(3) ni partículas ni ondas
(4) tanto partículas como ondas

Discussion and Solution:
Straight memorization.
Choice (4).

Problem 5

Which particles are not affected by the strong force?
(1) hadrons
(2) protons
(3) neutrons
(4) electrons

¿Qué partículas no son afectadas por la fuerza nuclear fuerte?
(1) hadrones
(2) protones
(3) neutrones
(4) electrones

Discussion and Solution:
Straight memorization.
Choice (4).