A motorcyclist started a race from START line and from rest, and accelerated with the acceleration of 2 m/s2 for 7 seconds. Then he increased the acceleration to 4 m/s2 and went with that acceleration for 8 seconds. What was the racer’s position from the START line after 7+8 seconds from the start of the race?

289 m .

Explanation:

s = ut + 1/2 at² , u is initial velocity , t is time , a is acceleration and s is distance covered .

For t = 7 s

s = 0 + 1/2 x  2 x 7²

= 49 m

velocity after 7 s

= a x t = 2 x 7 = 14 m /s

for next 8 s , initial velocity u = 14 m /s

S = ut + 1/2 at²

= 14 x 8 + 1/2 x 4 x 8²

= 112 + 128

= 240 m

Total displacement in 7 + 8 s

= 49 + 240 = 289 m .

another example of kinetic energy would be,

kinetic energy   >     moving energy

answer   >   letter choice (c),   a hammer falling off a table.

hope that !                                         : )

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia