CHEM 1R03 Lecture 1: SPH3U,T3L3,GPE

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28 Nov 2017

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The work done (against gravity) on an object equals the potential energy of the object at some height above the initial position. W = f d, where w = e g. E g = f d, where f = mg. E g = mgd, where d = h. Therefore, we can use this formula to determine the gravitational potential energy possessed by an object. E g = mgh m is the mass of the object in kg g is acceleration due to gravity in m/s2 or n/kg h is height in meters (m) As we lift something higher, it will possess more potential energy. Galileo wants to drop a 1. 5kg watermelon off of a 10m high roof. A 2. 35g penny is dropped from the observation deck of the cn tower.

Related Questions

The potential energy of water at the top of a dam or waterfall isconverted into heat when the water dashes against rocks at thebottom. The potential energy of the water at the top is equalto Ep=mgh,where m is the mass of the water, gisthe acceleration of the falling water due to gravity(g= 9.81 m/s2),and h is the height of the water.

Assuming that all the energy is converted to heat, calculate thetemperature rise of the water in degrees Celsius after falling overCalifornia

a.
The sun supplies energy at the rate of about 1.0 kilowatts persquare meter of earth (1 watt = 1 J/s). The plants in anagricultural field produce the equivalent of 20. kg of sucrose(C12H22O11) per hour per hectare (1 ha = 10,000 m2). Assume thatsucrose is produced by the reaction given below.
12 CO2(g) + 11 H2O(l) C12H22O11(s) + 12 O2(g) ?H = 5640 kJ
Calculate the percentage of sunlight used to produce the sucrose,that is, determine the efficiency of photosynthesis.
%

b.

On Easter Sunday, April 23, 1983, nitric acid spilled from a tankcar near downtown Denver, Colorado. The spill was neutralized withsodium carbonate.
2 HNO3(aq) + Na2CO3(s) 2 NaNO3(aq) + H2O(l) + CO2(g)
Calculate ?HÂ° for this reaction.
kJ
Approximately 5.0 104 gal nitric acid was spilled. Assume that theacid was an aqueous solution containing 50.0% HNO3 by mass with adensity of 1.42 g/cm3. How much sodium carbonate was required forcomplete neutralization of the spill? (?HfÂ° for NaNO3(aq) = -467kJ/mol.)
g
How much heat was evolved?
kJ
According to The Denver Post for April 4,1983, authorities fearedthat dangerous air pollution might occur during the neutralization.Considering the magnitude of ?HÂ°, what was their majorconcern?

c.
A piece of chocolate cake contains about 400 Calories. Anutritional Calorie is equal to 1000 calories (thermochemicalcalories), which is equal to 4.184 kJ. How many 9-inch-high stepsmust a 180 pound man climb to expend the 400 Cal from the piece ofcake? Assume that the energy used to climb steps is the same as theenergy required to lift a mass against the force of gravity,namely: PE = mgh, where m is the mass of the object lifted inkilograms, g is the gravitational constant (9.8 m/s2), and h is theheight the object is lifted in meters.
steps

CHEM 1R03 Lecture 1: SPH3U,T3L3,GPE

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