A small boat coasts at constant speed under a bridge. A heavy sack of sand is dropped from the bridge onto the boat. The speed of the boat:
a) A small boat coasts at constant speed under a bridge.
b) A heavy sack of sand is dropped from the bridge onto the boat.
c) The speed of the boat decreases.
d) increases.
e) does not change.
f) Without knowing the mass of the boat and the sand, we can't tell.

Explanation:

Let the mass of boat is m ad the initial velocity of the boat is u, the mass of sack is M and the velocity of boat after the sack is dropped in it is V.

As there is no external force acting on the system, so the linear momentum is conserved.

m x u = ( M + m) V

V = mu / ( M + m)

So, as M > m and the denominator is more than numerator so the velocity of the boat decreases.

Option (c) is correct.

weather forecasts are done by collecting data about the current state of the atmosphere mainly the temperature, humidity and wind and using meteorology, to determine the atmosphere that evolves over time. the h and l mean the high and low pressure. the red strip is a warm front. the blue strip is a cold front. the blue and red strip is a stationary front. the purple strip is a occluded front.

explanation:

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.