When work is done, an object changes its

What is the ﬁnal equilibrium temperature when 12 g of milk at 7◦C is added to 175 g of coﬀee at 69◦C? Assume the speciﬁc heats o

lina2011 [118]

Answer:

ﬁnal equilibrium temperature is 65.02 ◦C

Explanation:

Given data

milk = 12 g

temp milk = 7◦C

coffee = 175 g

coffee temp = 69◦C

to find out

ﬁnal equilibrium temperature

solution

we apply here equilibrium condition i.e m c ΔT

milk mass × c × ΔT = coffee mass × c × ΔT

12 × 1 × (T- 7) = 175 × 1 × ( 69- T)

12T - 84 = 12075 - 175 T

187 T = 12159

T = 65.02

so ﬁnal equilibrium temperature is 65.02 ◦C

3 0

4 years ago

I love making friends but i always feel lonely around them, i try to act fine and as if nothing bothers me but it does. I want a

arsen [322]

Answer:

i will be your friend ...

6 0

3 years ago

Read 2 more answers

A rock is thrown upward from a bridge into a river below. The function f(t)=−16t2+44t+88 determines the height of the rock above

babymother [125]

1) 88 ft

2) 4.09 s

3) 1.38 s

4) 118.2 m

Explanation:

1)

For an object thrown upward and subjected to free fall, the height of the object at any time t is given by the suvat equation:

$h(t) = h_0 + ut - \frac{1}{2}gt^2$ (1)

where

$h_0$ is the height at time t = 0

$u$ is the initial vertical velocity

$g=32 ft/s^2$ is the acceleration due to gravity

The function that describes the height of the rock above the surface at a time t in this problem is

$f(t)=-16t^2+44t+88$ (2)

By comparing the terms with same degree of eq(1) and eq(2), we observe that

$h_0 = 88 ft$

which means that the rock is at height h = 88 ft when t = 0: therefore, this means that the height of the bridge above the water is 88 feet.

2)

The rock will hit the water when its height becomes zero, so when

$f(t)=0$

which means when

$0=-16t^2+44t+88$

First of all, we can simplify the equation by dividing each term by 4:

$0=-4t^2+11t+22$

This is a second-order equation, so we solve it using the usual formula and we find:

$t_{1,2}=\frac{-b \pm \sqrt{b^2-4ac}}{2a}=\frac{-11\pm \sqrt{(11)^2-4(-4)(22)}}{2(-4)}=\frac{-11\pm \sqrt{121+352}}{-8}=\frac{-11\pm 21.75}{-8}$

Which gives only one positive solution (we neglect the negative solution since it has no physical meaning):

t = 4.09 s

So, the rock hits the water after 4.09 seconds.

3)

Here we want to find how many seconds after being thrown does the rock reach its maximum height above the water.

For an object in free fall motion, the vertical velocity is given by the expression

$v=u-gt$

where

u is the initial velocity

g is the acceleration due to gravity

t is the time

The object reaches its maximum height when its velocity changes direction, so when the vertical velocity is zero:

$v=0$

which means

$0=u-gt$

Here we have

$u=+44 ft/s$ (initial velocity)

$g=32 ft/s^2$ (acceleration due to gravity)

Solving for t, we find the time at which this occurs:

$t=\frac{u}{g}=\frac{44}{32}=1.38 s$

4)

The maximum height of the rock can be calculated by evaluating f(t) at the time the rock reaches the maximum height, so when

t = 1.38 s

The expression that gives the height of the rock at time t is

$f(t)=-16t^2+44t+88$

Substituting t = 1.38 s, we find:

$f(1.38)=-16(1.38)^2 + 44(1.38)+88=118.2 m$

So, the maximum height reached by the rock during its motion is

$h_{max}=118.2 m$

Which means 118.2 m above the water.

3 0

4 years ago

Identify the two functional groups that react to form polyester.

KiRa [710]

Polyester are commonly made up of an organic alcohol that contains a hydroloxyl and a carboxylic acid which contains a carboxyl. polyester is a class of synthetic polymers built up from multiple chemical repeating units linked together by ester groups. it also displays a wide array of properties and practical applications.

3 0

3 years ago

IN WHAT CONDITION DO SOUND ECHO

DerKrebs [107]

Answer:

The conditions necessary for hearing the echo. The distance between the sound source and the reflecting surface must not be less than 17 metres where the time period between hearing the original sound and its echo should not be less than 0.1 of a second.

6 0

3 years ago