200 Hz = 200 cycles per sec
<span>1 cycle, the period = 1/200 = 0.005 seconds, or 5 milli seconds.</span>
Answer:
51.85m/s
Explanation:
Given parameters:
Mass of ball = 0.0459kg
Force = 2380N
Time taken = 0.001s
Unknown:
Speed of the ball afterwards = ?
Solution:
To solve this problem, we use Newton's second law of motion:
F = m x 
F is the force
m is the mass
v is the final velocity
u is the initial velocity
t is the time taken
2380 = 0.0459 x 
0.0459v = 2.38
v = 51.85m/s
Answer:
Explanation:
a )
change in the gravitational potential energy of the bear-Earth system during the slide = mgh
= 45 x 9.8 x 11
= 4851 J
b )
kinetic energy of bear just before hitting the ground
= 1/2 m v²
= .5 x 45 x 5.8²
= 756.9 J
c ) If the average frictional force that acts on the sliding bear be F
negative work done by friction
= F x 11 J
then ,
4851 J - F x 11 = 756.9 J
F x 11 = 4851 J - 756.9 J
= 4094.1 J
F = 4094.1 / 11
= 372.2 N
Light that enters the new medium <em>perpendicular to the surface</em> keeps sailing straight through the new medium unrefracted (in the same direction).
Perpendicular to the surface is the "normal" to the surface. So the angle of incidence (angle between the laser and the normal) is zero, and the law of refraction (just like the law of reflection) predicts an angle of zero between the normal and the refracted (or the reflected) beam.
Moral of the story: If you want your laser to keep going in the same direction after it enters the water, or to bounce back in the same direction it came from when it hits the mirror, then shoot it <em>straight on</em> to the surface, perpendicular to it.
