PLS URGENT!!

The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°c _____.

Fiesta28 [93]

Answer:

4.2 J

Explanation:

Specific heat capacity: This is defined as the amount of a heat required to rise a unit mass of a substance through a temperature of 1 K

From specific heat capacity,

Q = cmΔt.............................. Equation 1

Where Q = amount of energy absorbed or lost, c = specific heat capacity of water, m = mass of water, Δt = Temperature rise.

Given: m = 1 g = 0.001 kg, Δt = 1 °C

Constant : c = 4200 J/kg.°C

Substitute into equation 1

Q = 0.001×4200(1)

Q = 4.2 J.

Hence the energy absorbed or lost = 4.2 J

6 0

3 years ago

You want the current amplitude through a 0.450-mH inductor (part of the circuitry for a radio receiver) to be 1.90 mA when a sin

faust18 [17]

Answer:

Frequency required will be 2421.127 kHz

Explanation:

We have given inductance $L=0.450H=0.45\times 10^{-3}H$

Current in the inductor $i=1.90mA=1.90\times 10^{-3}A$

Voltage v = 13 volt

Inductive reactance of the circuit $X_l=\frac{v}{i}$

$X_l=\frac{13}{1.9\times 10^{-3}}=6842.10ohm$

We know that

$X_l=\omega L=2\pi fL$

$2\times 3.14\times f\times 0.45\times 10^{-3}=6842.10$

f = 2421.127 kHz

6 0

3 years ago

A refrigerator having a power rating of 350W operates for 12 hours a day. calculate the cost of electrical energy to operate it

rodikova [14]

Answer:

See the answers below.

Explanation:

The cost of energy can be calculated by multiplying each given value, a dimensional analysis must be taken into account in order to calculate the total value of the cost in Rs.

$Cost=0.350[kW]*12[\frac{hr}{1day}]*30[days]*4.5[\frac{Rs}{kW*hr} ]=567[Rs]$

The fuse can be calculated by knowing the amperage.

$P=V*I$

where:

P = power = 350 [W]

V = voltage = 240 [V]

I = amperage [amp]

Now clearing I from the equation above:

$I=P/V\\I=350/240\\I=1.458[amp]$

The fuse should be larger than the current of the circuit, i.e. about 2 [amp]

3 0

3 years ago

A 2kg object weighs 19.6N on earth. If the acceleration due to gravity on mars is 3.71 meters per second what is the object mass

Gre4nikov [31]

The acceleration due to gravity at the Earth's surface is 9.8 m/s/s

So a 2 kg object will accelerate at 9.8 m/s/s if it is dropped..... actually all dropped objects will accelerate at the same rate. 

The force of gravity on the object is given by Newton's 2nd Law 

F = m . a 

F = 2 . 9.8 = 19.6 N 

Now go to Mars , with a lower gravitational field strength. It only accelerates falling objects at 3.71 m/s/s 

So the force of gravity on the object is F = 2 . 3.71 = 7.42 N 

But the answer is (2) 2 kg, because the mass of the object stays the same and that is what you are asked for. 
Someone was trying to be tricky.

3 0

3 years ago

During a safety test, a car hits a wall and stops in 0.55 s. The net force on the car is 6500 N during the collision. What is th

Kobotan [32]

Answer:

ΔP = 3600 kg m/s.

Explanation:

Change in momentum (ΔP) of the car is the amount of impulse on it. Impulse (I) can be define as the product of force and the time at which it acts.

i.e I = ΔP

But, I = Ft

Ft = ΔP

ΔP = 6500 x 0.55

= 3575 Ns

= 3600 kg m/ $s^{2}$ x s

ΔP = 3600 kg m/s

The magnitude of the change in momentum of the car is 3600 kgm/s.

6 0

3 years ago