10-cm-long wire is pulled along a U-shaped conducting rail in a perpendicularmagnetic field. The total resistance of the wire and rail is 0.20 Ω. Pulling the wire with aforce of 1.0 N causes 4.0 W of power to be dissipated in the circuit.

What is the speed of the wire when pulled with a force of 1.0 N?
What is the strength of the magnetic field?

Speed = 4m/s

Strength = 7.1T

Explanation: P= 4.0w

N = 1.0

V= ?

Power = force x velocity

Velocity = power/ force

V= 4.0w/1.0N

V = 4m/s

Strength of the magnetic field

B = √PR / lv

Where; l = length 10cm

R= 2.0

P= 4.0w

V= 4m/s

B = √ (4.0w) × (2.0) / (10cm) × (4m/s)

B = 7.1T

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.

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