Why can blue light and yellow light combine to produce white light?

How much heat does a freezer need to remove from 1kg of water at 40°C to make ice at 0°C? (You will need to use the specific hea

Montano1993 [528]

Answer:

Explanation:

Q = m c Δt

heat withdrawn to lower temperature by 40° C

Q = 1 X 1000 X 40 = 40,000 calories.

Q = mL

heat withdrawn to freeze water at 0°C to ice

= 1 x 80000 = 80,000 calories

total heat to be withdrawn = 120,000 calories. = 120,000 x 4.2 = 504 ,000 Joules.

3 0

3 years ago

Find the work done in pumping gasoline that weighs 6600 newtons per cubic meter. A cylindrical gasoline tank 3 meters in diamete

almond37 [142]

Answer:

work done in pumping the entire fuel is 1399761 J

Explanation:

weight per volume of the gasoline = 6600 N/m^3

diameter of the tank = 3 m

length of the tank = 6 m

The height of the tractor tank above the top of the tank = 5 m

The total volume of the fuel is gotten below

we know that the tank is cylindrical.

we assume that the fuel completely fills the tank.

therefore, the volume of a cylinder =

where r = radius = diameter ÷ 2 = 3/2 = 1.5 m

volume of the cylinder = 3.142 x x 6 = 42.417 m^3

we then proceed to find the total weight of the fuel in Newton

total weight = (weight per volume) x volume

total weight = 6600 x 42.417 = 279952.2 N

therefore,

the work done to pump the fuel through to the 5 m height = (total weight of the fuel) x (height through which the fuel is pumped)

work done in pumping = 279952.2 x 5 = 1399761 J

5 0

3 years ago

A decorative plastic film on a copper sphere of 10 mm diameter in an oven at 750C. Upon removal from the oven, the sphere is sub

AlladinOne [14]

Answer:

3.26 secs

Explanation:

Diameter of sphere ( D )= 10 mm

T1 = 75°C

P = 1 atm

T∞ = 23°C

T2 = 35°c

Velocity = 10 m/s

Determine how long it will take to cool the sphere to 35°C

Using the properties of copper and air given in the question

Nu = 2 + (Re)^0.8 (Pr)^0.33

hd / k = 2 + ( vd/v )^0.8 (Pr)^0.33

∴ h ≈ 2594.7 W/m^2k

Given that :

(T2 - T∞) / ( T1 - T∞ ) = exp [ ( -hA / pv CP ) t ]

( 35 - 23 ) / ( 75 - 23 ) = exp [ - 2594.7 * 6 * t / 8933 * 387 * 10 * 10^-3 ]

= ln ( 12/52 ) = -1.466337069 = - 0.45032919 * t

∴ t ≈ 3.26 secs ( -1.466337069 / -0.45032919 )

6 0

3 years ago

What is the processes called when matter, that is a liquid, transforms into a solid?

AURORKA [14]

Oh yeah I just got cheated lol lol lol lol

4 0

3 years ago

A student throws a set of keys vertically upward to her sorority sister, who is in a window 3.50 m above. The second student cat

Mkey [24]

Answer:

a) 8.58 m/s upward

b) -2.211 m/s downward

Explanation:

Let gravitational acceleration g = -9.81m/s2. This is negative because it deceleration the upward motion of the key.

(a)We have the following equation of motion

$s = v_0t + gt^2/2$

where $v_0$ is the initial upward velocity of the keys, t = 1.1s is the time it takes for the keys to travel a distance of s = 3.5 m

$3.5 = v_01.1 - 9.81*1.1^2/2$

$3.5 = 1.1v_0 - 5.94$

$1.1v_0 = 3.5 + 5.94 = 9.44$

$v_0 = 9.44 / 1.1 = 8.58 m/s$

So the keys were thrown initially upward with a speed of 8.58 m/s

(b) If the initial velocity of the key is 8.58 m/s and it is subjected to a deceleration of 9.81m/s2 for 1.1s then the velocity right at the 1.1s instant is

$v = v_0 + gt = 8.58 - 9.81*1.1 = -2.211 m/s$

So they keys would have a downward speed of 2.211 m/s

5 0

3 years ago