How long must a current of 100mA flow so as to transfer a charge of 80 C?
2 answers:
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Answer:
The speed of the wind is 25 km/hr.
Explanation:
Let us call the speed of the plane and
the speed of the wind. When the plane is flying against the wind, it covers the distance of 900-km in 2 hours (120 minutes); therefore;
(1).
And when the plane is flying with the wind, it covers the same distance in 1 hour 48 minutes (108 minutes)
(2).
From equation (1) we solve for and get:
,
and by putting this into equation (2) we get:
or in km/hr this is
Answer:
175.3 N
Explanation:
The motion of the ball is a uniform circular motion, therefore the net force on it must be equal to the centripetal force.
There are two forces acting on the ball at the lowest point of motion:
- The tension in the string, T , upward
- The weight of the ball, , downward
The net force (centripetal force) has the same direction as the tension (upward, towards the centre of the circular path), so we can write:
where the term on the right is the expression for the centripetal force, and where:
T is the tension in the string
is the weight of the ball
is the mass of the ball
v = 5.7 m/s is the speed of the ball at the lowest point
r = 4.4 m is the length of the rope, so the radius of the circle
Solving for T, we find the tension in the string: