Answer:
d. 3332.5 [N]
Explanation:
To solve this problem we will use newton's second law, which tells us that the sum of forces is equal to the product of mass by acceleration.
Here we have two forces, the force that pushes the car to move forward and the friction force.
The friction force is equal to the product of the normal force by the coefficient of friction.
f = N * μ
f = (m*g) * μ
where:
N = weight of the car = 2150*9.81 = 21091.5 [N]
μ = 0.25
f = (21091.5) * 0.25
f = 5273 [N]
Now as the car is moving forward, the car wheels move clockwise. The friction force between the wheels of the car and the pavement must be counterclockwise, i.e. counterclockwise. Therefore the direction of this force is forward. This way we have:
F + f = m*a
F + 5273 = 2150*4
F = 8600 - 5273
F = 3327 [N]
Therefore the answer is d.
Answer: A.
series or parallel
Explanation:
Total resistance across any branch of a circuit can be found by analyzing whether the branch is connected in series or parallel.
The resistors are connected either in series or parallel. Therefore, the resistance of resistors across a circle can be calculated in series and parallel.
Answer:
the answer, the correct one is C
Explanation:
Let's propose the solution of this problem to know which explanation is correct, when the concha stick with the disc is an impulse exercise
I = ΔP
∫ F dt = pf-po
∫ F dt = m v_f - m v₀
Therefore, during the time that the contact lasts, a force is applied to the disk, which causes that if the amount of movement increases and therefore its speed increases, when the constant ceases the forces are reduced to zero and the disk no longer changes its momentum following with constant velocity.
When reviewing the answer, the correct one is C
Answer:
f = v / 4L
the frequency of the instruments is reduced by the decrease in the speed of the wave with the temperature.
Explanation:
In wind instruments the wave speed must meet
v = λ f
λ = v / f
from v is the speed of sound that depends on the temperature
v = v₀
where I saw the speed of sound at 0ºC v₀ = 331 m/s the temperature is in degrees centigrade, we can take the degrees Fahrenheit to centigrade with the relation
(F -32) 5/9 = C
76ºF = 24.4ºC
45ºF = 7.2ºC
With this relationship we can see that the speed of sound is significantly reduced when leaving the house to the outside
at T₁ = 24ºC v₁ = 342.9 m / s
at T₂ = 7ºC v₂ = 339.7 m / s
To satisfy this speed the wavelength of the sound must be reduced, so the resonant frequencies change
λ / 4 = L
λ= 4L
v / f = 4L
f = v / 4L
Therefore, the frequency of the instruments is reduced by the decrease in the speed of the wave with the temperature.