You understand the concepts all perfectly fine, just have applied them slightly incorrectly.
Firstly, the speed time graph is actually a triangle since the question says a steady acceleration from rest - i.e. it started at 0 and worked up to 2ms-1 in the space of that 10 seconds. The area under the graph is the distance, and a triangle area is found with bh/2, and in this case that is 10*2/2 = 10m - so the boat travelled 10 metres.
Work done as you correctly stated is fd - giving the part against water resistance as 3*10 = 30J
However, you forgot to do the last part - the key words are rate of work - this means Power. Power is Energy/Time, and this whole process occurred over 10 seconds. So whilst 30J of energy were expended due to the water resistance, this didn't all occur in no time. So we need to divide that by 10 to get the power. And 30/10 is 3J/s - and J/s is the same as W.
I don’t know why it want let me say it so just comment on it !!
Answer:
a = 9.86 m/s²
Explanation:
given,
distance between the centers of wheel = 156 cm
center of mass of motorcycle including rider = 77.5 cm
horizontal acceleration of motor cycle = ?
now,
The moment created by the wheels must equal the moment created by gravity.
take moment about wheel as it touches the ground, here we will take horizontal distance between them.
then, take the moment around the center of mass. Since the force on the ground from the wheels is horizontal, we need the vertical distance.
now equating both the moment
m g d = F h
d is the horizontal distance
h is the vertical distance
m g d = m a h
term of mass get eliminated
g d = a h
so,


a = 9.86 m/s²
Answer: 200 knots
Explanation: the maximum indicated airspeed at which aircraft may be flown when at or below 2,500 feet AGL and within 4 nautical miles of the primary airport of Class C airspace is 200 KNOTS
It is B because the other ones are good.