On the calculation of Newton's law 1. A truck with a mass of 50000kg runs along a smooth horizontal road at a speed of 0.3m/s, with a rope trailing behind it. If the tension of the rope is 250N, how long does it take to stop the truck? 2. There is a speed limit sign of 30km / h in a certain section. After the driver makes an emergency brake in this section, the inspector measures that the length of the brake trace is 12m. If the dynamic friction coefficient between the tire and the road is 0.6, ask the driver whether he has violated the speed limit specified in this section of the road. (hint: calculate the acceleration when braking from the braking friction, and then calculate the initial speed from the kinematic formula.)

1.Ft=MV
250*t=50000*0.3
T = 60 seconds
2.0.6mg=ma
a=0.6g=5.88m/s2
a=0.5V2
V＝3.43m/s=12.3km/h
So there was no speeding

The operation of LG (a + b)

La plus LB

On LG calculation
For today's chemistry, the positive x-axis of the image is marked with -1.65, - 1.55, - 1.45 LG (SO4 concentration)
At that time, I thought that the negative value on the axis was increasing along the positive direction (i.e. - 1.45 ＞ - 1.55), then the concentration of SO4 was decreasing, and the result was wrong. How to calculate?

LG is a monotone increasing function, and the inverse function is also a monotone increasing function, - 1.45 > - 1.55, so the concentration is increasing,
In addition, the inverse function is 10 ^ X

What does LG mean in the sound pressure level formula
May I ask l_ P=20 lgP/P_0
In the formula
L_ P -- sound pressure level [DB];
P -- sound pressure [n / M ~ 2];
P_ 0 -- reference sound pressure, 2 × 10 ~ (- 5) [n / M ~ 2]
And if the engine noise is 2PA, how to calculate its sound pressure level?
If that elder brother knows, please give me advice
I kneel down

LG is a logarithm. It's a logarithm based on 10
L_ P=20 lg(2/2×10^-5)=20lg10^5=100

LG ^ 2 (2) what does LG ^ 2 stand for? Is there any formula?

LG ^ 2 (2) is actually [LG (2)] ^ 2

What does LG mean in astronomical formula
Like LG in M = - 2.5lge (E; apparent brightness, M: apparent magnitude)

Have you ever learned logarithm? LG is a common logarithm operation symbol. The meaning of LGE is the logarithm with E as the true number and 10 as the base. There is LG key (some are log) on the function calculator, you can directly press the answer. Before operation, you should pay attention to the unit of apparent brightness. Different units have different coefficients. For example, the apparent brightness of a star is 0.5: M =

What does LG in rainstorm intensity formula mean?

LG, denotes the logarithm based on 10 (commonly used logarithm), such as LG 10 = 1

Mathematics 1 / 2lg32 / 49-4 / 3lg √ 8 + LG √ 245

1/2lg32/49-4/3lg√8+lg√245
=(1/2)*(lg32-lg49) - (4/3)*(1/2)*lg8 +(1/2)*lg245
=(1/2)*(5lg2- lg49) - (2/3)*3lg2 +(1/2)*(lg49+lg5)
=(5/2)*lg2 - 2lg2 +(1/2)lg5
=(1/2)*(lg2+lg5)
=1/2

In p-abcd, PD ⊥ plane ABCD, ∠ CDA = ∠ DAB = 90 ° CD = 1, ad = 2, ab = 4, and ∠ APD = 30 ° m is the midpoint of Pb
① Verification: Pb ⊥ plane AMC;
② Find the distance from point a to plane PBC

① Prove: Pb ⊥ plane AMC; BD ⊥ AC is easy to prove, and BD is the projection of BP on the bottom, so. BP ⊥ AC. (1) ∠ APD = 30 °, then AP = 4, then ABP is isosceles right triangle, M is the midpoint of Pb, get: BP ⊥ am. (2) (if you calculate by numerical value, you can get BC = PC, M is the midpoint of Pb, also get: B

In the pyramid p-abcd, ABCD is a square, pad ⊥ on the side, ABCD on the bottom, PA = PD. It is proved that planar PAB ⊥ planar pad

Do PE ⊥ ad in e
Let e be EF ‖ and ab intersect BC with F
Because ABCD is a square
So ab ⊥ ad
Because of pad ⊥ bottom ABCD, p-ad-f is a straight dihedral angle, so PE ⊥ EF
And ef ‖ AB, so ab ⊥ PE
So ab ⊥ planar pad
The plane PAB goes through AB again
According to the judgment theorem: if a plane passes through a vertical line of another plane, the two planes are perpendicular to each other
Get proof