Answer:
Velocity ratio of a lever is 3 means distance travelled by effort is 3 times the distance travelled by the load. Efficiency of the pulley is 60%means 40% of the energy is lost in the machine due to the friction
Answer: The sum of an object's potential and kinetic energies is called the object's mechanical energy. As an object falls its potential energy decreases, while its kinetic energy increases. The decrease in potential energy is exactly equal to the increase in kinetic energy.
Refer to the figure shown below.
Let V = speed of the boat relative to the water
Given:
u = 1 km/h the speed of flowing water.
When traveling downstream from A to B, the actual speed of the boat is
V₁ = V + u = V + 1 km/h
When traveling upstream from B to A, the actual speed of the boat is
V₂ = V - u =V - 1 km/h
Because the distance Ab is 1 km, the time taken for the round trip is
t = (1 km)/(V+1 km/h) + (1 km)/(v-1 km/h)
= (V-1 + V+1)/(V² - 1)
= (2V)/(V² - 1)
The time for the round trip is 50 min = 5/6 h.
Therefore
(2V)/(V² - 1) = 5/6
5(V² - 1) = 12V
5V² - 12V - 5 = 0
Solve with the quadratic formula.
V = (1/10)*[12 +/- √(144 + 100)] = 2.762 or -0.362 km/h
Ignore negative speed, so that
V = 2.762 k/h
Answer:
The speed of the boat relative to the water is
2.76 km/h (nearest hundredth)
Answer:
50k is the km for this is the first send