For the water contained in a cylindrical container, a wooden block with a mass of 120g and a density of 0.6 × 1000kg / m * 3 is put into the water, and the water does not overflow out of the cup. (G is taken as 10N / kg for calculation): the volume of the wooden block immersed in the water after it is still

For the water contained in a cylindrical container, a wooden block with a mass of 120g and a density of 0.6 × 1000kg / m * 3 is put into the water, and the water does not overflow out of the cup. (G is taken as 10N / kg for calculation): the volume of the wooden block immersed in the water after it is still

The density of wood is less than that of water
From the analysis of buoyancy and force balance, it is concluded that gravity is equal to buoyancy;
F buoyancy = mg = P water g V drainage
Vdrainage = 0.00012 m3;
Because the water does not overflow, so V drainage is equal to the volume of wood into the water

When an object moves along a straight line, the distance it passes through at time t is s, the speed at the middle position s / 2 is V1, and the speed at the middle time t / 2 is V2, the relationship between V1 and V2 is
A when the object moves in a straight line with uniform acceleration, V1 > V2; B when the object moves in a straight line with uniform deceleration, V1 > v2
C when the object is moving in a straight line with uniform acceleration, v1

BC.
The velocity at the midpoint of the uniform acceleration motion is equal to the average velocity, V2 = s / T, and the displacement time of the first half of the uniform acceleration motion T1 > the second half of the uniform acceleration motion T2, so v1

(1) When the velocity of an object is large, the acceleration is not necessarily large
(2) The velocity of an object is zero, and the acceleration is not necessarily zero
(3) When the velocity of an object changes greatly, the acceleration is not necessarily large
(4) If the acceleration is negative, the object may not decelerate
(5) As the acceleration decreases, the velocity of the object does not necessarily decrease
(6) As the acceleration increases, the velocity of the object does not necessarily increase
(7) If the velocity of the object is constant, the acceleration may not be zero
(8) The direction of acceleration is not necessarily in line with the velocity

The object moving at a constant speed has no acceleration, but the speed can be very high. At the moment of hitting the ball hard, the ball is still, but there is a great acceleration. It doesn't say time. It's a very small acceleration, but the time is very long, and the speed changes greatly. I'm also entangled. When the acceleration is negative, I can only slow down. Because the speed changes, there will be acceleration

Senior one physics compulsory one pursuit problem specific explanation

There are two cases of pursuit problem: first, the speed is small (accelerating) and the speed is large (decelerating). When the speed is the same, the distance is the largest. Later, there is only one meeting (reaching the same position). Second, the speed is large (decelerating) and the speed is small (accelerating). When the speed is the same, it is the critical point

The questions are as follows
When the vehicle is running at the speed of 18m / s, after the emergency braking, it will make a uniform deceleration linear motion, and its acceleration is 4m / S2 (m every second power)
(1) The speed of the car when it rushes forward 38.5m after braking
(2) Vehicle speed at the end of 6S after braking
Thank you~

V0 & # 178; - vt & # 178; = 2As, the solution is VT = 4m / s
When the vehicle speed is reduced to 0, the time required is t = V0 / a = 4.5s, so the speed at the end of 6S is 0

In the formula v = V0 + at, four physical quantities are involved. Except that time t is a scalar, the other three V, V0 and a are all vectors. In linear motion, the directions of these three vectors are all on the same straight line. When the direction of one of the three vectors is positive, the directions of the other two quantities are the same as their positive values, and the opposite are negative values. If the direction of the initial velocity is positive, then The correct statement is ()
A. In uniform acceleration linear motion, the acceleration a takes negative value B. in uniform acceleration linear motion, the acceleration a takes positive value C. in uniform deceleration linear motion, the acceleration a takes positive value D. in both uniform acceleration linear motion and uniform deceleration linear motion, the acceleration a takes positive value

Take the initial velocity direction as the positive direction. When the object is moving in a straight line with uniform acceleration, the acceleration direction is the same as the velocity direction, and the acceleration is positive. When the object is moving in a uniform deceleration, the acceleration direction is opposite to the velocity direction, and the acceleration is negative. Therefore, B is correct, and a, C and D are wrong

It's better to have examples
Sick, no class, make up class

Halo, a square on a plane, gravity, plane support force, the two balance; on the slope, gravity, inclined downward tension, vertical slope support force, friction, friction direction is opposite to the direction of the tension, the four balance, gravity is decomposed into tension and pressure on the slope, the slope provides support force and produces friction
Generally, the force on inclined objects is classic. I learned something five years ago, but I didn't expect to remember it

What are two functions orthogonal to each other

Continuous functions f (x) and G (x) on [a, b] are "orthogonal" on [a, b], which usually means: ∫ [a, b] f (x) g (x) DX = 0

How to understand the sentence "a function has orthogonality"?

For example, trigonometric function. The product integral of two arbitrary functions is 0

Who knows the properties of orthogonal function
I know that in a certain interval, the integral of the product of two functions is 0, so these two functions are orthogonal, but what are the properties of these two orthogonal functions,