Gravitational force is determined by which of the following
1 answer:
Gravitational force is determined by mass
Answer: Option B
<u>Explanation:</u>
According to Universal law of gravity, the gravitational force is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between the objects.
Where,
G – gravitational constant =
= masses of two objects
r – distance between the objects
So, as per this law, the gravitational force is found by mass.
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Before going to solve this question first we have to understand specific heat capacity of a substance .
The specific heat of a substance is defined as amount of heat required to raise the temperature of 1 gram of substance through one degree Celsius. Let us consider a substance whose mass is m.Let Q amount of heat is given to it as a result of which its temperature is raised from T to T'.
Hence specific heat of a substance is calculated as-
Here c is the specific heat capacity.
The substance whose specific heat capacity is more will take more time to be heated up to a certain temperature as compared to a substance having low specific heat which is to be heated up to the same temperature.
As per the question John is experimenting on sand and water.Between sand and water,water has the specific heat 1 cal/gram per degree centigrade which is larger as compared to sand.Hence sand will be heated faster as compared to water.The substance which is heated faster will also cools faster.
From this experiment John concludes that water has more specific heat as compared to sand.
The velocity of the current in a river has no effect on the the time it takes to paddle a canoe across the river, given that the boat is pointed perpendicular to the bank of the river, because
The velocity of the river does not change the velocity and therefore the distance traveled in the direction of the boat which is directed perpendicular to it
Reason:
Let represent the velocity of the boat across the river in the direction,
, and let,
, represent the velocity of the river, we have;
The velocity of the boat perpendicular to the direction of the river =
Therefore, the distance covered per unit time in the perpendicular direction
to the flow of the river is , such that the time it takes to cross the river in
the perpendicular direction is the same, for every value of the velocity of
the river.
This is so because the velocity in the perpendicular direction to the flow of
the river, which is the velocity of the boat is unchanged by the velocity of
the river, because there is no perpendicular component of velocity in the
velocity of the river.
= 3 m/s
= 4 m/s
The width of the river, = 6 meters, we have;
- The resultant velocity =
The direction, θ, is given as follows;
The length of the path of the boat, <em>l</em>, is given as follows;
The length of the path the boat takes = 10 m
The time it takes to cross the river, t = , therefore;
- The time it takes to cross the river, t = 2 seconds
Considering only the y-components, we have;
Therefore;
Which expresses that the time taken is the same and given that the
vectors of the velocities of the river and the boat are perpendicular, the
distance covered in the direction of the boat is unaffected by the velocity
of the river.
Learn more vectors here: