Determine the mass of a ball with a velocity of 40.0 m/s and a wavelength of 8.92 ã 10-34 m.

The wavelength is equal to Planck's constant divided by the ball's momentum.
This means that:
lambda = h / p > equation I
Momentum = mass * velocity > equation II

Substitute by equation II in equation I, you get:
lambda = h / mv
Now, we are given:
lambda = 8.92 * 10^-34 m
Planck's constant = 6.625 * 10^-34
velocity = 40 m/sec

Substitute with these givens in the above equation to calculate the mass as follows:
8.92*10^-34 = (6.625*10^-34) / (40*m)
mass = 0.0185678 kg

Explanation:

(4566 m / 4 min) × (1 km / 1000 m) × (60 min / h) = 68.49 km/h