Answer:
The amount of kilograms of ice at -20.0°C that must be dropped into the water to make the final temperature of the system 40.0°C = 0.0674 kg
Explanation:
Heat gained by ice in taking the total temperature to 40°C = Heat lost by the water
Total Heat gained by ice = Heat used by ice to move from -20°C to 0°C + Heat used to melt at 0°C + Heat used to reach 40°C from 0°C
To do this, we require the specific heat capacity of ice, latent heat of ice and the specific heat capacity of water. All will be obtained from literature.
Specific heat capacity of ice = Cᵢ = 2108 J/kg.°C
Latent heat of ice = L = 334000 J/kg
Specific heat capacity of water = C = 4186 J/kg.°C
Heat gained by ice in taking the total temperature to 40°C = mCᵢ ΔT + mL + mC ΔT = m(2108)(0 - (-20)) + m(334000) + m(4186)(40 - 0) = 42160m + 334000m + 167440m = 543600 m
Heat lost by water = mC ΔT = 0.25 (4186)(75 - 40) = 36627.5 J
543600 m = 36627.5
m = 0.0674 kg = 67.4 g of ice.
<h3><u>Answer;</u></h3>
B. 3.43 kPa
<h3><u>Explanation</u>;</h3>
Pressure is given by the formula;
Pressure = Force / Area
Force is the product of mass and acceleration due to gravity.
Thus; Force = mass x acceleration due to gravity
Substituting;
Force = (350 kg) x (9.8 m/s²)
Force = 3430 N
Then, using the first equation;
Pressure = 3430 N / 1m² or Pa
<h3> <u>= 3.43 kPa</u></h3>
Answer:
Density of unknown material = 3.86 g/cm³
Explanation:
Mass of unknown material, M = 54 gm
The object occupied 14 gm of water.
Volume of unknown material = Volume of 14 gm of water.
Density of water = 1 gm/cm³
Volume of 14 gm of water
Volume of unknown material, V = Volume of 14 gm of water = 14 cm³
Density of unknown material
(a) If the balloon is suspended in air and it drifts neither up nor down, it means the forces acting on it are equally balanced. There are only two forces acting on the balloon:
- its weight, of magnitude 1 N, directed downward
- the buoyant force, directed upward
The two forces are balanced, so the buoyant force in this case is equal to the weight of the balloon: 1 N.
(b) when the buoyant force decreases, the weight becomes greater than the buoyant force. This means there is now a net force on the balloon, acting downward, so the balloon starts to drift toward the ground.
(c) when the buoyant force increases, it becomes greater than the weight. This means there is now a net force on the balloon, acting upward, so the balloon starts to go up.
Answer:
The kinetic energy of the cell phone is 9J
Explanation:
The kinetic energy is the energy possessed by a body by virtue of motion.
The kinetic energy is expressed as
KE= 1/2m(v)²
Given data
Mass of cell phone m= 80g--to kg=80/1000= 0.08kg
Velocity of cell phone v= 15m/s
Substituting our given data we have
KE= 1/2*0.08(15)²
KE= (0.08*225)/2
KE=18/2
KE= 9J