Answer:
B. He should change the lengths of the vectors that point tangent to the circle so that each is the same length. 
Explanation:
A uniform circular motion is a motion in a circle where the tangential speed of the object is constant.
In the motion map:
- The arrows pointing towards the centre of the circle represent the centripetal acceleration, and their length represent the magnitude of the acceleration
- The arrows pointing tangential to the circle represent the tangential speed, and their length represent the magnitude of the speed
In this motion map, we see that the length of the vectors pointing tangent to the circle is not constant: this means that the speed is not constant. In order to have a uniform circular motion, the speed must be constant, therefore the lengths of the vectors that point tangent to the circle must be the same.
 
        
                    
             
        
        
        
An instrument used to observe or imagine very small object using an optical mangifier
 mirco cell.
Telescope is a magnifer of distance object
        
             
        
        
        
 Answer:
150000000000 m
0.0000005 seconds
33.33 ns
Explanation:
Speed of electromagnetic waves through vacuum = 
Echo time = 1000 seconds
Echo time is the time taken to reach the object and come back to the observer
Distance = Speed×Time

Venus is 150000000000 m away from Earth
Time = Distance / Speed

Echo time will be twice the time

The echo time will be 0.0000005 seconds
Difference in time = Difference in distance / Speed

The accuracy by which I will be able to measure the echo time is 33.33 ns
 
        
             
        
        
        
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  
 
        
             
        
        
        
Answer:
Magnetic force, attraction or repulsion that arises between electrically charged particles because of their motion. It is the basic force responsible for such effects as the action of electric motors and the attraction of magnets for iron. Electric forces exist among stationary electric charges; both electric and magnetic forces exist among moving electric charges. The magnetic force between two moving charges may be described as the effect exerted upon either charge by a magnetic field created by the other.