The acceleration of the boat is 
(eastward)
Explanation:
We can solve this problem by using Newton's second law, which states that:
F = ma (1)
where
F is the net force on a body
m is its mass
a is its acceleration
First of all, we have to find the net force acting on the boat. We have:
- The force of the motor, 100 N eastward
- The force of the air resistance, 60 N westward
So the net force is:
F = 100 N - 60 N = 40 N (eastward)
Now we can apply eq.(1), using:
F = 40 N
m = 20 kg (mass of the boat)
and solving for a, we find the acceleration:
And the direction is the same as the net force (eastward).
Learn more about acceleration and Newton laws of motion:
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Answer:
Explanation:
Velocity of sound in air at 20 degree = 343 m/s
Velocity of sound in water at 20 degree = 1470 m/s
Time taken in to and fro movement in air
=( 2 x 10) / 343 = 0.0583 s
Rest of the time is
.171 - .0583 = .1127 s
This time is taken to cover distance in water. If d be the depth of lake
2d / velocity = time taken
2 d / 1470 = .1127
d = 82.83 m
Answer:
351 ohm
720 ohm
Explanation:
When c and d are open:
Terminals c and d are open.. If you redraw the circuit as below, you can see that the two resistors in the first column are in parallel as, they are connected together at both pairs of terminals (due to the short).
Hence, we have a pair of parallel resistors:
Req1 = (R1*R2)/ (R1 + R2) = 360*540/(360+540) = 216 ohms
Req2 = (R3*R4)/ (R3 + R4) = 180*540/(180+540) = 135 ohms
Now these two sets are in series with another Hence,
Req = Req1 + Req2 = 216 + 135 = 351 ohms
Answer: 351 ohms
When c and d are shorted:
The current will flow through the least resistant path naturally from resistors R3 and R1 or R4.
Both of these resistor lie in a single path placing the resistors in series to one another, hence
Req = R3 + R1 = 180 + 540 = 720 ohms
Answer:720 ohms
