The simplest answer is that gravity is the field created by a mass distribution in the spacetime around it; gravitational force is the force exterted by the field on a test mass in the field.
Answer:
12900 W
24200 W
Explanation:
Given:
v₀ = 0 m/s
v = 1.3 m/s
t = 2.0 s
Find: a and Δx
v = at + v₀
(1.3 m/s) = a (2.0 s) + (0 m/s)
a = 0.65 m/s²
Δx = ½ (v + v₀) t
Δx = ½ (1.3 m/s + 0 m/s) (2.0 s)
Δx = 1.3 m
While accelerating:
Newton's second law:
∑F = ma
F − mg = ma
F = m (g + a)
F = (1500 kg + 400 kg) (9.8 m/s² + 0.65 m/s²)
F = 19855 N
Power = work / time
P = W / t
P = Fd / t
P = (19855 N) (1.3 m) / (2.0 s)
P ≈ 12900 W
At constant speed:
Newton's second law:
∑F = ma
F − mg = 0
F = mg
F = (1500 kg + 400 kg) (9.8 m/s²)
F = 18620 N
Power = work / time
P = W / t
P = Fd / t
P = Fv
P = (18620 N) (1.3 m/s)
P ≈ 24200 W
Answer:
a) 3000 Hz;
b) 30 dB;
c) 1000 times.
Explanation:
a) From the human audiogram given on the figure below the black line represents the threshold for hearing the sound at each frequency. We see that the least intensity is necessary for the frequency of about 3000 Hz.
b) Using the same audiogram we see that we would need the sound of the intensity of about 30dB.
c) The least perceptible sound at 1000 Hz must be 0dB while at 100 Hz it is 30dB. These are logarithmic quantities. To transform them to the linear quantities we use the formula
where 
is the hearing threshold at 1000 Hz.
Therefore we have the following
is the threshold at 1000Hz and 
is the threshold at 100Hz.
By exponentiating we have
Now dividing these two equations we get
Therefore, the least perceptible sound at 100Hz is 1000 times more intense than the least perceptible sound at 1000Hz.
Note: I got these values unisng the audiogram that is attached here. The one that you have might be slightly different and might yield different answers.
Answer:
A)The electric field at a point cannot be in two different directions and therefore two field lines can never cross.
E)If equipotential lines of different potentials cross that would imply that the potential at that point has two different values and that is not physically possible.
Explanation:
A) Field lines cannot be crossed. Otherwise, at the point where the lines cross, there would be two different electric field vectors, which makes no physical sense.
E) Since the electric field is a conservative vector field, it can be defined as the negative value of the gradient of the electric potential, therefore, the same is true as in the previous point.
Gravitational potential energy is the energy stored in an object due to its height above the Earth.
Explanation:
Gravitational potential energy is an energy that an object has as a result of its position in a gravitational field.
For an object which is near to Earth surface is gravitational acceleration is considered to be constant at 9.8 m/s².
Gravitational potential energy is also defined as the amount of work done to move an object having certain mass from one point to another point against gravitational force. It is calculated as mass multiplied by height to which an object is moved.
Some examples are water stored in a dam, ball kept on the top of a ramp, book kept of a shelf, etc.
