Answer:
a. The total momentum of the trolleys which are at rest before the separation is zero
b. The total momentum of the trolleys after separation is zero
c. The momentum of the 2 kg trolley after separation is 12 kg·m/s
d. The momentum of the 3 kg trolley is -12 kg·m/s
e. The velocity of the 3 kg trolley = -4 m/s
Explanation:
a. The total momentum of the trolleys which are at rest before the separation is zero
b. By the principle of the conservation of linear momentum, the total momentum of the trolleys after separation = The total momentum of the trolleys before separation = 0
c. The momentum of the 2 kg trolley after separation = Mass × Velocity = 2 kg × 6 m/s = 12 kg·m/s
d. Given that the total momentum of the trolleys after separation is zero, the momentum of the 3 kg trolley is equal and opposite to the momentum of the 2 kg trolley = -12 kg·m/s
e. The momentum of the 3 kg trolley = Mass of the 3 kg Trolley × Velocity of the 3 kg trolley
∴ The momentum of the 3 kg trolley = 3 kg × Velocity of the 3 kg trolley = -12 kg·m/s
The velocity of the 3 kg trolley = -12 kg·m/s/(3 kg) = -4 m/s
The velocity of the brick is 39.2 m/s downward
Explanation:
The motion of the brick is a free fall motion, since the object is affected only by the force of gravity. Therefore, it has a uniformly accelerated motion towards the ground, with constant acceleration of 
.
So, we can find its velocity using the suvat equation:
where
v is the final velocity
u is the initial velocity
a is the acceleration
t is the time
For the brick in this problem (taking downward as positive direction)
u = 0 (it is dropped from rest)
Therefore, its velocity after t = 4.0 s is:
Downward, because the sign is positive.
Learn more about free fall motion:
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Since the outer plumage of the penguin can resist the flow of heat in the cold antarctic air they might gain a little of this heat to keep them warm by thermal convection.
<u>Explanation:</u>
- Convection is the circular movement that happens when hot air/liquid moves with molecules that were fast, making it less dense rises while the cold air/liquid drops down.
- Also, they follow the technique of standing together always in a group which further helps them to decrease the loss of heat between them.
- The plumage of penguin provides 80 percent of total insulation and is highly resistant to wind penetration.
The basic relationship between frequency of an electromagnetic wave and wavelength of the wave is
where
is the speed of light.
Manipulating the equation, we can rewrite it as
The frequency of the wave in our problem is
so if we use the previous formula, we find the correspondant wavelength:
Answer:
solids cannot flow because the molecules a held tightly together
