Senior 1 Physics Questions Seeking Answers The answers must be accurate

1.An object moves in a straight line at a uniform variable speed The magnitude of the velocity at a certain moment is 4m s and the velocity becomes 10m s after moving 12m, and the object is in this distance.

The time required for AD is t=12*2 (4+10) s = acceleration magnitude a=(10-4) =

2.The energy reduction of the piercing plank is e=1 2 m (v1 -v2) and the same three fixed planks are pierced, 3e=1 2 v3 2e=1 2 v11

e=1/2 v22²

The answer to the first question is a and d time = 12 = 12 7 =

Acceleration = (10-4).

I'm thinking about the second question, but I don't have a pen at hand.

Don't listen to them, the first question d is wrong, it refers to the magnitude of acceleration, and the direction is not stated, so it should be discussed by category. I don't really want to do this kind of calculation in front of the computer, and there are no points.

Select CD for analysis. The object doesn't move in a straight line at a constant velocity, so a is wrong (if you think about it, if the key flutter had been 0 before, the displacement would have been less than 2m).

b can also be excluded in this way. C's words he said maybe, cave oak is right, D's words have a premise of uniform linear motion, and the draft is also accurate.

The temperature t1 = 300 K in the c state, v1

The standard condition is auspicious, and the temperature t0=273k, v0

v0/t0=v1/t1

v0=v1*t0/t1=

This is the volume of the gas under standard conditions.

n=（v0/

v0 you didn't talk about in the title, it's a useful piece of paper.

Let the speed of the person relative to the ground be v1, the speed of the ladder person relative to the ground is v2, and the number of steps of the ladder is n, when the ladder is up, the speed relative to the ladder is v=v1-v2

v1=v+v2

The time to ascend the ladder is: t=n1 v

Relative to the ground, from the first floor to the second floor must pass the n-level, so t=n v1=n1 (v+v2).

It is available from above. n1/v=n/(v+v2)

1) When going down the ladder: the speed relative to the ladder is v=v1+v2v1=v-v2

The time to descend is: t=n2 v

Relative to the ground, from the second floor to the first floor, you must pass the n-level, so t=n v1=n (v-v2).

It is available from above. n2/v=n/(v-v2)

2) (1) (2) add the reciprocal to get:

n=2n1n2/(n1+n2)

Set the elevator upward speed v, and the walking speed of people u. When the actual progression is n up, the upstairs speed is only the sum of the two speeds, t=n (v+u), and for people, t=n1 u

So n (v+u) = n1 u

Similarly, n (v-u) = n2 u

The solution is n=2n1*n2 (n1+n2).

The displacement of the object in three seconds is the old GT = 45m (just 3 seconds to reach the ground), the velocity of the object is: 30m s, and the kinetic energy is MV = 450J

S average power: 450J 3S=150W;

The displacement in the third second is: 45-20=25m, and the average missing power in the third second is mgh 1s=25j.

The instantaneous power at the end of the third second is: MV = 450W;

From the second one, the volt rises: 25m from the ground is exactly the end of 2s, the speed is 20m s, and the gravitational instantaneous power.

is mv =200j