In a laboratory experiment, you wish to determine the initial speed of a
dart just after it leaves a dart gun. The dart, of mass m (0.04 kg), is fired
with the gun very close to a wooden block of mass Mo (=1.5 kg) which
hangs from a cord of length l (= 2m) and negligible mass, as shown.
Assume the the dart is moving horizontally when it hits the left side of the
block at its center and becomes embedded in it. The block swings up to a
maximum angle of 20° from the vertical.

a. Determine the speed vo of the dart immediately before it strikes the
block.

b. The dart and block subsequently swing as a pendulum. Determine the tension in the cord when it returns to
the lowest point of the swing.