Electromagnetic wave bc I studied that early in the year
Answer:
C. At the instant the ball reaches its highest point.
Explanation:
When a body is thrown up, it tends to come down due to the influence of gravitational force acting on the body. The body will be momentarily at rest at its maximum point before falling. At this maximum point, the velocity of the body is zero and since force acting on a body is product of the mass and its acceleration, the force acting on the body at that point will be "zero"
Remember, F = ma = m(v/t)
Since v = 0 at maximum height
F = m(0/t)
F = 0N
This shows that the force acting on the body is zero at the maximum height.
By Snell's law:
η = sini / sinr. i = 25, η = 1.33
1.33 = sin25° / sinr
sinr = sin25° / 1.33 = 0.4226/1.33 = 0.3177 Use a calculator.
r = sin⁻¹(0.3177)
r ≈ 18.52°
Option A.
God's grace.
Answer:
F = 768 N
Explanation:
It is given that,
Speed of the elevator, v = 3.2 m/s
Grain drops into the car at the rate of 240 kg/min, 
We need to find the magnitude of force needed to keep the car moving constant speed. The relation between the momentum and the force is given by :
Since, the speed is constant,
F = 768 N
So, the magnitude of force need to keep the car is 768 N. Hence, this is the required solution.
