Answer:
Explanation:
Given that,
The frequency of local AM radio station, f = 696 KHz = 696000 Hz
We need to find the energy of the frequency at which it is broadcasting.
We know that,
Energy of a wave, E = hf
Where
h is Planck's constant
Put all the values,
So, the energy of the wave is equal to.
(a) -2451 N
We can start by calculating the acceleration of the car. We have:
is the initial velocity
v = 0 is the final velocity of the car
d = 125 m is the stopping distance
So we can use the following equation
To find the acceleration of the car, a:
Now we can use Newton's second Law:
F = ma
where m = 1100 kg to find the force exerted on the car in order to stop it; we find:
and the negative sign means the force is in the opposite direction to the motion of the car.
(b)
We can use again the equation
To find the acceleration of the car. This time we have
is the initial velocity
v = 0 is the final velocity of the car
d = 2.0 m is the stopping distance
Substituting and solving for a,
So now we can find the force exerted on the car by using again Newton's second law:
As we can see, the force is much stronger than the force exerted in part a).
1) He has both potential and kinetic energy
2) Before the parachute opens, the potential energy decreases and the kinetic energy increases
Explanation:
1)
The gravitational potential energy of a body is the energy possessed by the object due to its position in a gravitational field, and it is given by:
where
m is the mass of the body
g is the acceleration of gravity
h is the height of the body above the ground
On the other hand, the kinetic energy of a body is the energy possessed by the body due to its motion; it is given by
where
v is the speed of the object
Here Mr. Leppold has both potential and kinetic energy before opening the parachute, because:
- It is moving at a certain speed, so , therefore he has kinetic energy
- He is at a certain height above the ground, , therefore he has potential energy
2)
The total mechanical energy of Mr.Leppold is the sum of the potential and the kinetic energy:
According to the law of conservation of energy, in absence of air resistance, this quantity remains constant.
During the fall, the height of Leppold decreases: this means that as decreases, the potential energy decreases too.
However, the total energy E must remain constant: therefore, this means that the kinetic energy KE must increase, and this occurs because the speed of Mr. Leppold increases as he falls.
Learn more about kinetic and potential energy:
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