Answer:
0.41
Explanation:
A 49 N block has a mass of 5 kg:
49/9.8
A horizontal force of 50 N giving it an acceleration of 6 m/s^2 means that 30 N is taken up by the acceleration
This leaves 20 N to take care for friction. so the coefficient of friction is:
20/49 = 0.41.
The average speed <em>appears to be</em> (distance) / (time) =
(length of the cable) / (time from when a pulse goes in until it comes out the other end) .
That's 1,200,000 meters/ 0.006 second = 2 x 10^8 = <em>2 hundred million m/sec</em>
That figure is about 66.7% of the speed of light in vacuum.
The reason I went through all of this detail was to point out that this is
NOT necessarily the speed of light in this glass, for two reasons.
1). The path of light through an optical fiber is not straight down the middle. In the original fibers of 20 or 30 years ago, the light bounced back and forth off the inside walls of the fiber, and zig-zagged its way along the length. In current modern fibers, it still zig-zags, but it's a more gentle, up-and-down curved path. In either case, the distance covered by the light inside the fiber is more than the straight length of the cable, and the time it takes it to come out the other end is more than its actual speed inside the glass would have meant if it could have traveled straight through the pipe.
2). This problem talks about an optical fiber that's 1,200km long. There is loss in optical fiber, and you're NOT going to get light all the way through a single piece of it that's something like 745 miles long. It takes electronic repeaters, "boosters", and regenerators every few miles to keep it going, and these devices add "latency" or time delay in the process of going through them. That delay in the electronics shows up as apparent delay through the fiber-optic cable, and it makes the speed through the glass appear to be slower than it actually is.
The answer is kinetic energy
The answer is
-Small f and large D.
The explanation:
-when The car jack is an example of a machine, which is defined as anything that a person can use to make the exertion of force easier.
-So with the small force he exerts on the jack, the distance that the car is lifted up increases
.
and People needs help of machines to increase their force. People cannot lift a car without a machine. Using the leverage or hydraulic principles the machines increase your force.
If you use a large leverage you execute a large movement with little force and as result the other side will move small distances with a greater force.
