Vectors
What is the definition of a resultant vector?
A single vector having the same effect as two or more vectors together
Distance and displacement both measure length, but they are different types of physical quantities. What is the fundamental difference between the two?
Distance is a scalar quantity, while displacement is a vector quantity.
Give a precise definition of the normal force.
The normal force is the force or the component of a force exerted by a surface on an object in contact with it, acting perpendicular to the surface
In volumetric analysis, what exactly is a standard solution?
A standard solution is a solution whose exact concentration is known.
What is the correct IUPAC suffix for a hydrocarbon chain that contains at least one carbon-carbon double bond?
-ene.
A force of 400 N acts on an object at an angle of 60° above the horizontal. Calculate the exact magnitude of the horizontal component of this force.
Rx=400cos(60∘)= 200 N
A body starts from rest and reaches a velocity of 5 m/s after travelling with uniform acceleration for exactly 2 seconds. Calculate its acceleration.
a=tv−u=
25−0=
2.5 m/s²
State Newton’s First Law of Motion in words.
A body will remain in its state of rest or motion at constant velocity unless a non-zero resultant/net force acts on it
A student prepares 250 cm³ of a 0.2 mol/dm³ standard solution of Sodium Carbonate (Na2CO3). Calculate the exact number of moles of Sodium Carbonate floating in this flask
n=c×V
n=0.2×0.250 dm3
= 0.05 moles.
Provide the correct IUPAC name for a 4-carbon straight-chain alkane that has a single chlorine atom attached to the second carbon.
2-chlorobutane.
A pilot aims his plane due East at 50 m/s while a crosswind blows due North at 20 m/s. Calculate the exact magnitude of the plane's resultant velocity.
Using Pythagoras: R=sqrt(502+202)= 53.85 m/s
A motorist is travelling at 30 m/s when he suddenly hits the brakes and comes to a complete rest in 3.3 seconds. Calculate the deceleration of the car.
v=u+at
0=30+a(3.3)
a=3.3−30= -9.09 m/s²
What is the definition of a frictional force, and does it act parallel or perpendicular to the surface the object is in contact with?
Frictional force is the force that opposes the motion of an object, and it acts parallel to the surface the object is in contact with
A mystery compound is analyzed and found to contain 40.0% Carbon, 6.66% Hydrogen, and 53.3% Oxygen by mass. Determine its empirical formula
CH2O.
Working: Assume 100g. Moles C = 3.33, H = 6.66, O = 3.33.
Divide all by 3.33 to get a 1:2:1 ratio.
Give the IUPAC name for a positional isomer of pent-1-ene
pent-2-ene.
A force P of magnitude 250 N acts at an angle of 10° to the horizontal. Calculate both the horizontal (x) and vertical (y) components of this force P.
Horizontal (FPx) = 250cos(10∘)= 246.20 N.
Vertical (FPy) = 250sin(10∘)= 43.41 N.
A car starting from rest accelerates steadily and reaches a velocity of 20 m/s in exactly 10 seconds. Assuming the acceleration is constant, calculate the total distance travelled by the car.
s=2(u+v)t
s=2(0+20)×10
= 100 m.
You are pulling a heavy block across a flat floor using a rope. If you increase the angle of the rope (meaning you pull more upwards, away from the floor), what happens to the magnitude of the normal force and the frictional force? Do they increase, decrease, or remain the same?
They both decrease.
By pulling upwards at a steeper angle, you lift some of the weight off the floor, which decreases the normal force.
Since friction is proportional to the normal force, the frictional force also decreases
During a reaction, a chemist calculates a theoretical yield of 88.3 g of zinc nitrate. However, after evaporating the water, she physically isolates only 65.2 g. Calculate the percentage yield.
Percent yield=(65.2/ 88.3)×100= 73.84%.
To which homologous series does 2,2-dimethylbutane belong, and what is the general formula for this series?
It belongs to the Alkanes. The general formula is CnH2n+2.
Two forces of magnitudes 8 N and 6 N are added to each other. Which of the following values CANNOT be a resultant of these two forces: 2 N, 3 N, 14 N, or 16 N? Explain why?
16 N. The maximum possible resultant is when they act in the same direction (8+6=14 N) and the minimum is when they act in opposite directions (8−6=2 N). 16 N falls outside this possible range
A motor cyclist travelling at 12 m/s applies the brakes and decelerates uniformly at 3 m/s² until coming to a complete stop. Calculate both the time it takes him to stop, and his total braking distance.
Time: v=u+at→0=12+(−3)t
t= 4 seconds.
Distance: v2=u2+2as
0=122+2(−3)s
6s=144
s= 24 meters
A 3 kg block is pulled horizontally across a flat, rough surface. If the coefficient of kinetic friction (μk) between the surface and the block is 0.15, calculate the exact magnitude of the kinetic frictional force acting on the block.
First find the normal force: N=mg=3×9.8=29.4 N. T
hen find kinetic friction: Fk=μkN=0.15×29.4= 4.41 N
A student needs to prepare exactly 500 cm³ of a 0.25 mol/dm³ standard solution of Sodium Carbonate (Na2CO3). Calculate the exact mass of solid Na2CO3 the student must weigh out on the scale (Molar masses: Na=23, C=12, O=16).
Molar mass Na2CO3=(23×2)+12+(16×3)=106 g/mol.
Moles needed = 0.25×0.500 dm3=0.125 mol.
Mass = 0.125×106= 13.25 g.
Name this molecule: A 7-carbon continuous chain containing a triple bond starting at carbon 2, and a single chlorine atom attached to carbon 5.
5-chlorohept-2-yne.