The widely accepted hypothesis before that turned out wrong was the Earth-Centered theory or the Geocentric Theory. This was proposed by the philosopher Ptolemy. He came about to this hypothesis from hi observation that from the Earth's perspective, the celestial bodies like the Sun, stars and the moon, look like they rotate around the Earth each day and night. However, this was disproved by Galileo Galelei by his Heliocentric Theory. He observed through the telescope that the Venus also changes phases like the moon. However, he deduced that this is not possible from the positions of the Venus, Earth, Moon and Sun.
first we make a U turn and travel towards home in t = 20 s
so the distance of home from initial position is


Now after picking up the book we travel back with speed 20 m/s
so again after t = 20 s the displacement is given as

so the net displacement is given as


so it will be displaced by total displacement 200 m
Answer: 8.1 x 10^24
Explanation:
I(t) = (0.6 A) e^(-t/6 hr)
I'll leave out units for neatness: I(t) = 0.6e^(-t/6)
If t is in seconds then since 1hr = 3600s: I(t) = 0.6e^(-t/(6 x 3600) ).
For neatness let k = 1/(6x3600) = 4.63x10^-5, then:
I(t) = 0.6e^(-kt)
Providing t is in seconds, total charge Q in coulombs is
Q= ∫ I(t).dt evaluated from t=0 to t=∞.
Q = ∫(0.6e^(-kt)
= (0.6/-k)e^(-kt) evaluated from t=0 to t=∞.
= -(0.6/k)[e^-∞ - e^-0]
= -0.6/k[0 - 1]
= 0.6/k
= 0.6/(4.63x10^-5)
= 12958 C
Since the magnitude of the charge on an electron = 1.6x10⁻¹⁹ C, the number of electrons is 12958/(1.6x10^-19) = 8.1x10^24 to two significant figures.
Answer:
a) The maximum possible acceleration the truck can give the SUV is 7.5 meters per second squared
b) The force of the SUV's bumper on the truck's bumper is 18000 newtons
Explanation:
a) By Newton's second law we can find the relation between force and acceleration of the SUV:

With F the maximum force the truck applies to the SUV, m the mass of the SUV and a the acceleration of the SUV; solving for a:

b) Because at this acceleration the truck's bumper makes a force of 18000 N on the SUV’s bumper by Third Newton’s law the force of the SUV’s bumper on the truck’s bumper is 18000 N too because they are action-reaction force pairs.
Explanation:
- A substance will floats if it is having lower density than the density of the liquid in which it is placed.
- A substance will sink if it is having density greater than the density of the liquid in which it is kept.
Density of corn syrup = 
1) Density of gasoline = 
Density of the gasoline is less than the the density of corn syrup which means it will float in corn syrup.
2) Density of water = 
Density of the water is less than the the density of corn syrup which means it will float in corn syrup.
3) Density of honey = 
Density of the gasoline is more than the the density of corn syrup which means it will sink in corn syrup.
4) Density of titanium = 
Density of the titanium is more than the the density of corn syrup which means it will sink in corn syrup.