Two boats start together and race across a 60-km-wide lake and back. Boat A goes across at 60 km/h and returns at 60 km/h. Boat B goes across at 30 km/h, and its crew, realizing how far behind it is getting, returns at 90 km/h. Turnaround times are negligible, and the boat that completes the round trip first wins. (a)Which boat wins and by how much? (Or is it a tie?) (b) What is the average velocity of the winning boat?

Explanation:

a) Boat A wins as it crosses the finish line at the same time Boat B makes its turn around.

Say the lake was 60 km wide

Boat A takes a time of 120 km / 60 km/hr = 2 hrs to finish the race

Boat B takes a time of 60/30 + 60/90 = 2 + 2/3 hrs to finish the race

Boat A wins by 60 km or 2/3 hr which is 40 minutes.

In general, Boat A will win by the length of the lake and a significant amount of time.

average velocity of the winning boat is 0 km/hr as velocity is displacement over time. As the start and finish are at the same point, there is no displacement. Average speed, which is distance over time is 60 km/hr.

gpe = mass x gravity constant x height or… gpe = mgh

where… mass: measured in kilograms (kg)

gravity: gravity constant on earth = 10.00 m/s2

height: measured in meters (m)

gpe: measured in joules (j) or kilojoules (kj)

how do you solve gpe?

gravitational potential energy (gpe) is the energy an object has because of its position above the. ground.

gpe = mass x gravity constant x height or… gpe = mgh.

mass:

note: to earn full marks when solving science word problems, you must show your work:

formula.

example:

given values:

mass = 0.3 kg.