4. An airplane normally flies at 240 km/hr. If it experiences a 80 km/hr tailwind then its resultant velocity will be km/hr.

Its resultant velocity will be 320 km/h.

Explanation:

The tail wind is called the wind that brings greater speed to an airplane, because it has the same direction as the airplane and, therefore, contributes a positive force to the force that the airplane's engines print on it.

Thus, a tailwind adds its speed to the speed of the plane, developing a resulting speed higher than that marked on the air transport speedometer.

In the case, given that the speed of the plane is 240 km / h and the tail wind is 80 km / h, the resulting speed will be 320 km / h.

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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