Energy and Work
State the formula for Work (W)
W = Fd
State whether the following statement is true or false: Energy can be created but can never be destroyed.
False - Energy can never be created nor destroyed, only changed from one form to another.
Thermal energy of an object depends on...
Mass, temperature, and specific heat
State the ideal gas law formula for moles.
PV = nRT
Which object has a larger kinetic energy: a 300 kg object moving at 50 m/s or a 1500 kg
object moving at 20 m/s?
The first object
A 4.5 kg ball is dropped from a height of 2.4 meters. Assuming there is no air resistance, calculate the velocity of the ball just before it hits the ground.
v = 6.86 m/s
The average body temperature is generally accepted as 37ºC. Represent this temperature in ºF.
TF = 98.6 ºF
How many molecules are in 3 cubic meters of air at room temperature and atmospheric pressure?
N = 7.5 ∙ 1025
You carry an 8 kg bag of groceries 1.25 m above the ground at constant speed across a 6 m room. How much work do you do on the bag in the process?
W = 0 J
A Toyota Prius with a mass of 1400 kg with a speed of 20 m/s moves downhill and hits an initially uncompressed horizontal spring with a spring constant of 7 × 105 N/m that is located on a plain down the hill. What is the maximum distance the spring
compresses?
x = 0.8 m
The heat required for raising the temperature of a lead ball from 15ºC to 25ºC is 288 J. Find the mass of the ball (specific heat of lead is 128 J ∙ kg-1 ∙ K-1).
m = 0.225 kg
An ideal gas has a pressure of 2.5 atm and a volume of 1 L at a temperature of 20°C. How many molecules are there in this gas? (R = 8.31 J ∙ mol-1 ∙ K-1, 1 atm = 101 kPa, NA = 6.02 × 1023).
n = 6.24 ∙ 1022 moles
A 1000 kg car experiences a net force of 9500 N while slowing down from 30 m/s to 15.9 m/s. How far does it travel while slowing down?
d = 34 m
One of the world's most famous roller coasters "Formula Rossa" of mass 4000 kg starts from rest at the top of a hill with a height of 50 meters. Additionally, there's a spring mechanism, the spring constant of which is 400 N/m, and at the bottom of the hill that compresses 3 meters upon impact. Assuming there's no friction, calculate the speed of the roller coaster car at the bottom of the hill.
v = 31.3 m/s
A person tries to heat up their bath water by adding 5 L of water at 80°C to 60 L of water at 30°C. What is the final temperature of the bath water?
Tf = 33.9°C
A gas has a volume of 18 L at 93.1 kPa and 281 K. What is the volume of the gas at STP?
V2 = 0.0017 m3
Qabil pulls his little brother Ismail along the horizontal ground in a wagon. He exerts a force on the wagon of 600 N at an angle of 37° above the horizontal. If he pulls her a distance of 12 m, how much work does Qabil do?
W = 566.8 J
A skateboard with a mass of 4 kg is released at the top of a 3 m ramp. At the bottom of the ramp, there's 2 m of rough surface that causes a friction force of 10 N (the rest of the ramp is frictionless). Calculate the maximum height of the skateboard on the other side of the ramp after passing through the rough surface once.
h = 3.51 m
A lab student drops a 300 g piece of metal at 120.0°C into a cup containing 500 g of water at 20.0°C. After waiting for a few minutes, the student measures that the final temperature of the system is 40.0°C. What is the specific heat of the metal, assuming that no significant heat is exchanged with the surroundings or the cup? (The specific heat of water is 4186 J ∙ kg-1 ∙ K-1).
Cp = 1255.8 J ∙ kg-1 ∙ K-1
A large balloon filled with Helium gas has a volume of 137 L at 96.8 kPa and 31.6°C. At what temperature will the balloon have a volume of 180 L if held at a pressure of 87.3 kPa?
T2 = 361.1 K