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Alex73 [517]
3 years ago
7

Một nười thả 420g chì ở nhiệt độ 100°C và 260g nước ở nhiệt độ 58°C làm cho nước nóng lên tới 60°C . Cho nhiệt dung riêng của nư

ớc là 4200J/kg.K và bảo qua sự hao phí nhiệt ra môi trường bên ngoài . Hãy tính :
a) Nhiệt độ của chì khi có cân bằng nhiệt

b) Nhiệt lượng nước đã thu vào

c) Nhiệt dung riêng của chì

d) Nếu muốn nước và chì nóng tới nhiệt độ 75°C thì cần thêm vào một lượng chì ở nhiệt độ 150°C là bao nhiêu ?
Physics
1 answer:
vlabodo [156]3 years ago
6 0
Hey what language is this?
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1. A 2.5 kg led projector is launched as a projectile off a tall building. At one point, as it
spin [16.1K]

Answer:

Explanation:

I got everything but i. Don't know why but it's eluding me. So let's do everything but that.

a. PE = mgh so

   PE = (2.5)(98)(14) and

   PE = 340 J

b. KE=\frac{1}{2}mv^2 so

   KE=\frac{1}{2}(2.5)(14)^2 and

   KE = 250 J

c. TE = KE + PE so

   TE = 340 + 250 and

   TE = 590 J

d. PE at 8.7 m:

   PE = (2.5)(9.8)(8.7) and

   PE = 210 J

e. The KE at the same height:

   TE = KE + PE and

   590 = KE + 210 so

   KE = 380 J

f. The velocity at that height:

   380=\frac{1}{2}(2.5)v^2 and

   v=\sqrt{\frac{2(380)}{2.5} } so

   v = 17 m/s

g. The velocity at a height of 11.6 m (these get a bit more involed as we move forward!). First we need to find the PE at that height and then use it in the TE equation to solve for KE, then use the value for KE in the KE equation to solve for velocity:

   590 = KE + PE and

   PE = (2.5)(9.8)(11.6) so

   PE = 280 then

   590 = KE + 280 so

   KE = 310 then

   310=\frac{1}{2}(2.5)v^2 and

   v=\sqrt{\frac{2(310)}{2.5} } so

   v = 16 m/s

h. This one is a one-dimensional problem not using the TE. This one uses parabolic motion equations. We know that the initial velocity of this object was 0 since it started from the launcher. That allows us to find the time at which the object was at a velocity of 26 m/s. Let's do that first:

   v=v_0+at and

   26 = 0 + 9.8t and

   26 = 9.8t so the time at 26 m/s is

   t = 2.7 seconds. Now we use that in the equation for displacement:

   Δx = v_0t+\frac{1}{2}at^2 and filling in the time the object was at 26 m/s:

   Δx = 0t + \frac{1}{2}(-9.8)2.7)^2 so

   Δx = 36 m

i. ??? In order to find the velocity at which the object hits the ground we would need to know the initial height so we could find the time it takes to hit the ground, and then from there, sub all that in to find final velocity. In my estimations, we have 2 unknowns and I can't seem to see my way around that connundrum.

4 0
3 years ago
An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector
Ghella [55]

Answer:

a = 5.05 x 10¹⁴ m/s²

Explanation:

Consider the motion along the horizontal direction

v_{x} = velocity along the horizontal direction = 3.0 x 10⁶ m/s

t = time of travel

X = horizontal distance traveled = 11 cm = 0.11 m

Time of travel can be given as

t = \frac{X}{v_{x}}

inserting the values

t = 0.11/(3.0 x 10⁶)

t = 3.67 x 10⁻⁸ sec

Consider the motion along the vertical direction

Y = vertical distance traveled = 34 cm = 0.34 m

a = acceleration = ?

t = time of travel  = 3.67 x 10⁻⁸ sec

v_{y} = initial velocity along the vertical direction = 0 m/s

Using the kinematics equation

Y = v_{y} t + (0.5) a t²

0.34 = (0) (3.67 x 10⁻⁸) + (0.5) a (3.67 x 10⁻⁸)²

a = 5.05 x 10¹⁴ m/s²

7 0
3 years ago
A 1520 kg car is rolling<br> down a frictionless<br> 14.4° slope. What is<br> its acceleration?
Umnica [9.8K]

Answer:

a = 2.44 m/s²

Explanation:

The Net force acting on the car downwards the plane will be equal to the component of the weight that is parallel to the plane.

Thus;

mg(sin θ) = ma

Thus;. g(sin θ) = a

g is acceleration due to gravity = 9.81 m/s²

θ = 14.4°

Thus;

9.81 × sin 14.4 = a

a = 2.44 m/s²

7 0
2 years ago
You are travelling by skateboard at 3.0 m/s and start to accelerate. If you
vovangra [49]

Answer: 8m/s

Explanation:

Vs= 3 m/s

Vf=?

a=0.5m/s²

t=10s

-----------

a=Vf-Vs/t

at=Vf-Vs

0.5*10s=Vf-Vs

5m/s=Vf-3m/s

5m/s+3m/s=Vf

Vf=8m/s

6 0
3 years ago
Is Nuclear Energy renewable or nonrenewable? Use in your own words.
Talja [164]
It is non renewable because at nuclear power plants, the steam is created from the heat that produced from the plant. Because it is produced from a source that is not automatically renewable over the time, it is considered not to be a renewable source.
5 0
3 years ago
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