Answer:
1) from the positive x-axis.
2)
Explanation:
Given:
speed of rowing in still water,
1)
speed of water stream,
we know that the direction of resultant of the two vectors is given by:
where:
the angle of resultant vector from the positive x-axis.
angle between the given vectors
When the rower wants to reach at the opposite end then:
so,
from the positive x-axis.
2)
Now the resultant velocity of rowing in the stream:
Therefore time taken to cross a 4 miles wide river:
Momentum is the product of mass and velocity.
Thus, P=mv
where,
P is momentum.m is mass of the body.v is velocity of the body.
Answer: B = 1380T
Explanation: please find the attached file for the solution
Answer:
(a i - 2a j) / 2
Explanation:
a1 = a i
a2 = a j
a3 = - (i + j) (2a) = - 2a i - 2a j
a4 = (i - j) (3a) = 3a i - 3a j
Let the mass of each particle is m.
Use the formula of acceleration of centre of mass
a cm = (m1 a1 + m2 a2 + m3 a3 + m4 a4) / (m1 + m2 + m3 + m4)
a cm = (a i + aj - 2a i - 2a j + 3a i - 3a j) / 4
a cm = ( 2a i - 4a j) / 4
a cm = (a i - 2a j) / 2
Answer:
A. The sound wave will reflect off Buildings and automobiles.
Explanation:
This is because the sound waves would more likely propagate through diffraction through buildings and transmission through the air. It is also more likely to be absorbed by buildings than for multiple reflections to occur off buildings and automobiles. In the process of reflection, these materials would absorb the sound energy thereby reducing its ability to reflect.