Answer:
x = 1474.9 [m]
Explanation:
To solve this problem we must use Newton's second law, which tells us that the sum of forces must be equal to the product of mass by acceleration.
We must understand that when forces are applied on the body, they tend to slow the body down to stop it.
So as the body continues to move to the left, it is slowing down. Therefore we must calculate this deceleration value using Newton's second law. We must perform a sum of forces on the x-axis equal to the product of mass by acceleration. With leftward movement as negative and rightward forces as positive.
ΣF = m*a
Now using the following equation of kinematics, we can calculate the distance of the block, before stopping completely. The initial speed must be 100 [m/s].
where:
Vf = final velocity = 0 (the block stops)
Vo = initial velocity = 100 [m/s]
a = - 3.39 [m/s²]
x = displacement [m]
Answer:
Microwave: Radiation
Water: Conduction, convection & radiation.
Explanation:
- When we heat a food using microwave then the water content of the food is only heated by the microwave.
- Microwaves make the molecules of water vibrate frequently with a frequency closer to the frequency of microwaves and this increases the kinetic energy of the molecules which produces heat in the water molecules this heat then propagates to the whole food by conduction and convection, but the heat enters the food only via radiation.
Now when the food item is kept into warm water then the molecules closer to the food heat the food by conduction through direct energy transfer by lattice vibrations and when they become cooler than the mass of water all around then due to density difference they settle down and their place is occupied by warmer molecules around in the fluid leading to convection.
Radiation of energy from a mass occurs continuously irrespective of the medium present there. So the heat of water also enters the food by radiation of energy from the water molecules.
Answer:
13.5 ms
Explanation:
The sound wave travels with uniform motion in both cases, so the time taken to cover a distance d is given by:
where
d is the distance to cover
v = 340 m/s is the speed of sound in air
So for the people across the newsroom,
d = 4.7 m
So the time taken is
The radio waves instead travels with uniform motion at the speed of light:
So the time taken for them is
where
d = 82 km = 82,000 m
is the distance of the people who are 82 km away. Substituting,
Therefore, the difference in time is
1. Frequency:
The frequency of a light wave is given by:
where
is the speed of light
is the wavelength of the wave
In this problem, we have light with wavelength
Substituting into the equation, we find the frequency:
2. Period:
The period of a wave is equal to the reciprocal of the frequency:
The frequency of this light wave is (found in the previous exercise), so the period is:
Answer:
All the hairs on the child's head must gain the same type of charge. Like charges repel so the strands of hair experience a force that pushes them away from each other.
Explanation:
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