Answer:
69.68 N
Explanation:
Work done is equal to change in kinetic energy
W = ΔK = Kf - Ki =
W =
where m = mass of the sprinter
vf = final velocity
vi = initial velocity
W = workdone
kf = final kinetic energy
ki = initial kinetic energy
d = distance traveled
Ftotal = total force
vf = 8m/s
vi= 2m/s
d = 25m
m = 60kg
inserting parameters to get:
W = ΔK = Kf - Ki =
= 39.7
we know that the force the sprinter exerted F sprinter, the force of the headwind Fwind = 30N
Explanation :
Magnetic field, B = 5.2 T
Electric field,
The directions of the two fields are perpendicular to each other. Hence the force due to each field will equate each other.
Electrostatic force, F =qE.........(1)
Magnetic force, F = qvB........(2)
From equation (1) and (2)
E = v B
Hence, the correct option is (a).
(2) A permanent magnet always has two poles as the North pole and south pole. The magnetic field lines start from north poles and terminate at the south pole of the magnet.
Hence, the correct option is (C).