D = distance between the cars at the start of time = 680 km
v₁ = speed of one car
v₂ = speed of other car = v₁ - 10
t = time taken to meet = 4 h
distance traveled by one car in time "t" + distance traveled by other car in time "t" = D
v₁ t + v₂ t = D
(v₁ + v₂) t = D
inserting the values
(v₁ + v₁ - 10) (4) = 680
v₁ = 90 km/h
rate of slower car is given as
v₂ = v₁ - 10
v₂ = 90 - 10 = 80 km/h
Answer:
B. 47-54 miles/hour
Explanation:
Gale is a strong wind which is depicted by red warning flag. According to U.S. National Weather Service gale is a sustained surface wind. It is also used to refer winds from tropical coastal areas.
On the basis of force of wind gale is divided in four groups:
- Near gale - 32-38 mph
- Gale - 39-46 mph
- Strong gale - 47-54 mph
- Storm - 55-63 mph
The electrostatic force between two charges q1 and q2 is given by
where
is the Coulomb's constant
is the distance between the two charges.
In our problem, the two charges are two electrons, so their charges are equal and equal to
By substituting these values, we find the intensity of the force between the two electrons:
This is the magnitude of the force each electron exerts to the other one. The direction is given by the sign of the charges: since the two electrons have same charge, they repel each other, so the force exerted by electron 1 is toward electron 2 and viceversa.
The question is incomplete. Here is the complete question.
A floating ice block is pushed through a displacement vector d = (15m)i - (12m)j along a straight embankment by rushing water, which exerts a force vector F = (210N)i - (150N)j on the block. How much work does the force do on the block during displacement?
Answer: W = 4950J
Explanation: <u>Work</u> (W), in physics, is done when a force acts on an object that has a displacement form a place to another:
W = F · d
As the formula shows, Work is a scalar product, i.e, it results in a number, so, Work only has magnitude.
Force and displacement for the ice block are in 2 dimensions, then work will be:
W = (210)i - (150)j · (15)i - (12)j
W = (210*15) + (150*12)
W = 3150 + 1800
W = 4950J
During the displacement, the ice block has a work of 4950J
Answer;
C. geothermal power
Explanation;
Geothermal power is considered to be a sustainable, renewable source of energy because the heat extraction is small compared with the Earth's heat content. It depends the least on weather.
Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.
