Please help me with this!!

Explanation:

∑Fx = 0

F1 + F2 = 0

-12 + 2 = -10

force acting against the block is Fx = 10N to the right.

Force = mass * acceleration

where acceleration = 2.0 meters per second.

                       force = 10 N

                      mass = ??

plugin values into the formula:

10 = mass * 2.0

mass = 10 / 2.0

mass = 5 kg

mass on the block = 5kg.

wavelength divides in half and speed stays the same.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg