a) A ball of mass 20 g moving at horizontal speed of 20 m s' hits a vertical wall. The ball bounces back on the same path with the same speed after touching the wall for 0.01 s. i) Calculate the total changes of momentum of the ball. ii) Calculate the average force exerted by the ball on the wall. iii) Is this collision elastic or inelastic? Prove your answer. b) From (a), if the ball bounces back with half its initial speed on the same path, calculate i) the change of momentum of the ball. ii) the change of kinetic energy of the ball.​

the answer to this question is 60 n

iron would move it is magnetic there is a mag field around the current in the wire

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

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min