We have the relation

where
denotes the velocity of a body A relative to another body B; here I use B for boat, E for Earth, and R for river.
We're given speeds


Let's assume the river flows South-to-North, so that

and let
be the angle made by the boat relative to East (i.e. -90° corresponds to due South, 0° to due East, and +90° to due North), so that

Then the velocity of the boat relative to the Earth is

The crossing is 153.0 m wide, so that for some time
we have

which is minimized when
so the crossing takes the minimum 30.0 s when the boat is pointing due East.
It follows that

The boat's position
at time
is

so that after 30.0 s, the boat's final position on the other side of the river is

and the boat would have traveled a total distance of

Wood, marble, clay, terracotta and even concrete all come in colors and can be classified as natural materials.
An object in motion will stay in motion, therefore the person will still be going the same speed as the car was going before the collision
The correct answer is D He could pull the mass down farther.
Amplitude, is the maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. So to increase the amplitude the spring should be pulled down further which can increase the amplitude.
Velocity = Displacement / time
Displacement = 450 - 150 = 300.
By the time he walked 150 East, he walked backwards. Hence displacement is 300 m West.
Velocity = 300m / 300 s
= 1 m/s