-- The truck begins the scenario moving at 6 m/s.
-- After increasing its speed at the rate of 2 m/s² for 12 seconds,
it has gained (2 x 12) = 24 m/s of speed, and it's then moving
at 30 m/s.
-- The truck's average speed during the 12 seconds is (1/2) (6 + 30) = 18 m/s
-- Traveling at an average speed of 18 m/s for 12 seconds,
the truck travels
(18 m/s) x (12 sec) = 216 meters
<h3><u>
For the aceleration:</u></h3>
First, let's find the resultant, and <u>applicate 2nd law of Newton</u> using the resultant, so:
R = ma
F - Ff = ma
Data:
F = Force = 1150 N
Ff = Friction force = 490 N
m = Mass = 150 kg
a = Aceleraction = ?
Replacing according our data:
1150 N - 490 N = 150 kg * a
660 N = 150 kg * a
660 N / 150 kg = a
a = 4,4 m/s² ← Aceleration of the object
<h3><u>For the normal force:</u></h3>
The normal force IS NOT the resultant force, the normal force's the force between the ground and the object, in another words, is the weight of the object, and for the weight:
w = mg
w = 150 kg * 10 m/s²
w = 1500 N ← Normal force between object and ground.
Explanation:
It is known that octane is a hydrocarbon and London dispersion forces are the main intermolecular forces which are present in it.
Whereas water molecules tend to form hydrogen bonding forces which are actually much stronger than dipole-dipole interactions. This means that more energy is necessary to separate water molecules from one another than to separate octane molecules from one another.
Hence, we can conclude that surface tension of octane is expected to be lower than that of water when the two are considered at the same temperature.