We call it a "green" leaf because green light bounces off of it and enters our eyes. Other colors of light are absorbed by the leaf and stop right there.
If there's no green light to bounce off of the leaf, then no light at all comes from it.
When we look at an object that has no light coming from it, we describe the object as "black". We only know it's there because of its background and surroundings.
(Choice - A)
Answer:
a) A = 4.0 m
, b) w = 3.0 rad / s
, c) f = 0.477 Hz
, d) T = 20.94 s
Explanation:
The equation that describes the oscillatory motion is
x = A cos (wt + fi)
In the exercise we are told that the expression is
x = 4.0 cos (3.0 t + 0.10)
let's answer the different questions
a) the amplitude is
A = 4.0 m
b) the frequency or angular velocity
w = 3.0 rad / s
c) angular velocity and frequency are related
w = 2π f
f = w / 2π
f = 3 / 2π
f = 0.477 Hz
d) the period
frequency and period are related
T = 1 / f
T = 1 / 0.477
T = 20.94 s
e) the phase constant
Ф = 0.10 rad
f) velocity is defined by
v = dx / dt
v = - A w sin (wt + Ф)
speed is maximum when sine is + -1
v = A w
v = 4 3
v = 12 m / s
g) the angular velocity is
w² = k / m
k = m w²
k = 1.2 3²
k = 10.8 N / m
h) the total energy of the oscillator is
Em = ½ k A²
Em = ½ 10.8 4²
Em = 43.2 J
i) the potential energy is
Ke = ½ k x²
for t = 0 x = 4 cos (0 + 0.1)
x = 3.98 m
j) kinetic energy
K = ½ m v²
for t = 00.1
²
v = A w sin 0.10
v = 4 3 sin 0.10
v = 1.98 m / s
Answer:
E. It will decrease because the charge will move in the direction of the electric field.
Explanation:
The electric potential energy decreases uniformly as the charge move away in the direction of the field. Since a positive charge that experiences a force in the direction of an electric field increases its kinetic energy at the expense of its electric potential energy.
Momentum has a magnitude and a direction.
Its magnitude is (mass) x (magnitude of the velocity)
Its direction is the same as the direction of the velocity.
The thing you should memorize is: Momentum = (mass) x (velocity). P=mv
Answer:
Explanation:
Let assume that ball's motion is frictionless and its geometric dimensions can be neglected. Besides, it is assumed that ball begins at a height of zero. The ball can be modelled by means of the Principle of Energy Conservation:
The initial speed of the ball is: