How many football fields (including the 10 yards in each end zone) would it take to make a mile?

What type of device forms images through refraction?

Tcecarenko [31]

Answer:

A lens

Explanation:

A lens forms images when light passes Through it bending the rays of in the process.A phenomena called refraction and the speed of light changes in the process because it enters a medium since it's wavelength is reduced.

3 0

1 year ago

The current in some DC circuits decays according to the function I=I0e−t/τ, where I is the current at some point in time, I0 is

almond37 [142]

Answer: 1.95

Explanation:

You should start off from the decay formula and solve for τ:

$I = I_{0}e^{\frac{t}{\tau\\ } }$

$\frac{I}{I_{0}} = e^{\frac{-t}{\tau} }$

Apply inverse logarithmic function:

$ln(\frac{0.2 A}{1.2 A} ) = \frac{-t}{\tau}$

The final form will be:

$\tau=\frac{-3.5s}{ln(\frac{0.2A}{1.2A} )}$

Inputing values for I, IO, and t:

$\tau=\frac{-3.5S}{ln(\frac{0.2 A}{1.2 A} )} = 1.95$

3 0

3 years ago

Question 17 A sample of iron is put into a calorimeter (see sketch at right) that contains of water. The iron sample starts off

ivanzaharov [21]

Complete Question:

A 59.1 g sample of iron is put into a calorimeter (see sketch attached) that contains 100.0 g of water. The iron sample starts off at 85.0 °C and the temperature of the water starts off at 23.0 °C. When the temperature of the water stops changing it's 27.6 °C. The pressure remains constant at 1 atm.

Calculate the specific heat capacity of iron according to this experiment. Be sure your answer is rounded to the correct number of significant digits

(Question attached)

Answer:

$c_{iron}=0.568 J/kg.\°C$

$c_{iron}=0.6 J/kg.\°C$ (rounded to 1 decimal place)

Explanation:

A calorimeter is used to measure the heat of chemical or physical reactions. The example given in the question is using the calorimeter to determine the specific heat capacity of iron.

When the system reaches equilibrium the iron and water will be the same temperature, $T_{e}$ . The energy lost from the iron will be equal to the energy gained by the water. It is assumed that the only heat exchange is between the iron and water and no exchange with the surroundings.

$Q=mc(T_{e}-T_{initial})$ (Eq 1)

$-Q_{iron}=Q_{water}$ (Eq 2)

Water:

$m_{water}=100.0 g, c_{water}=4.186 J/kg.\°C, T_{initial,water}=23 \°C, T_{e}=27.6 \°C$

Iron:

$m_{iron}=59.1 g, c_{iron} = ? J/kg.\°C, T_{initial,iron}=85 \°C, T_{e}=27.6 \°C$

Substituting Eq 1 into Eq 2 and details extracted from the question:

$-m_{iron}c_{iron}(T_{iron,e}-T_{initial})=m_{water}c_{water}(T_{water,e}-T_{initial})$

$-59.1*c_{iron}(27.6-85)=100.0*4.186(27.6-23)$

$c_{iron}=0.568 J/kg.\°C$

$c_{iron}=0.6 J/kg.\°C$

4 0

3 years ago

A 25 kg cart has 125 kg*m/s of momentum. How fast is the car going?

PSYCHO15rus [73]

Therefore, the car is moving with a velocity of 5 m/s.

7 0

2 years ago

Read 2 more answers

A 0.11 kg bullet traveling at speed hits a 18.3 kg block of wood and stays in the wood. The block with the bullet imbedded in it

arlik [135]

Explanation:

The energy of the system before the collision must equal the energy after the collision.

After the collision the bullet and the block have a total mass of 18.41 kg and they move at a speed of 8.8 m/s. The kinetic energy after the collision is

$\frac{18.41 kg (8.8 m/s)^2}{2} = 713 J$

Before the collision only the bullet has kinetic energy.

So we can now determine the speed of the bullet using

$\frac{0.11kg (v^2)}{2} = 713 J\\v = 114 m/s$

5 0

2 years ago