Answer: 
Explanation:
IMA stands for Ideal Mechanical advantage.
The IMA of pulley system can be defined as the ratio of output force to input force.
From the given pulley system,
The input force = 
The output force = 
Hence, IMA of the given pulley system,

The magnetic field lines due to a straight, current-carrying wire are circular.
<u>Explanation:</u>
The concepts of Electromagnetism brought a new revolution to the science world. The idea is the source of many new modes of power and machines that reduces the manual work. Motors are the best example of machines that run on the concepts of electromagnetism. So the concept is that a current-carrying conductor induces a magnetic field in its nearby premise.
This magnetic field can perceive by the magnetic line of forces. Now, if we pour some iron dust around a current-carrying conductor, we'll see a concentric circular pattern around the straight wire whose centre will be at the conductor axis. The pattern of these magnetic lines of force may deflect with the variation of current in the wire but remain in the circular format.
Answer:
He traveled 9km
Explanation:
To do this problem you need to use the equation which is Speed= distance/time and this problem gives you the speed which is 18 km/h and it gives you the time 1/2 hour so you write the equation 18= d/ 1/2 which his distance is 9km