1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
erica [24]
3 years ago
13

Bob can row 14 mph in still water. The total time to travel downstream and return upstream to the starting point is 4 hours. If

the total distance downstream and back is 42 miles, determine the speed of the river (current speed).
Physics
1 answer:
bija089 [108]3 years ago
7 0

Answer:

7 mph

Explanation:

Let the speed of river is c mph.

The effective downstream speed = 14 + c

The effective upstream speed = 14 - c

Total time = 4 hrs

Total distance = 42 miles

Time for upstream + time for downstream = 4 hrs

21 / (14 + c) + 21 / (14 - c) = 4

21 (14 - c + 14 + c) = 4 (196 - c^2)

21 x 28 = 4 (196 - c^2)

c^2 = 196 -147 = 49

c = 7 mph

You might be interested in
A 2.50-m segment of wire carries 1000 A current and feels a 4.00-N repulsive force from a parallel wire 5.00 cm away. What is th
Stolb23 [73]

Answer:

The current is  I_b  =  400 \ A

Explanation:

From the question we are told that

    The  length of the segment is  l  =  2.50  \  m

     The current is  I_a  =  1000 \ A

     The force felt is  F  =  4.0 \  N

        The distance of the second wire is  d =  5.0 \ cm  = 0.05 \  m

Generally the current on the second wire is mathematically represented as

        I_b  =  \frac{2 \pi * r * F }{ l *  \mu_o  *  I_a }

Here  \mu_o is the permeability of free space with value  \mu_o =  4 \pi * 10^{-7} \ N/A^2

=>      I_b  =  \frac{2 * 3.142  *  0.05 *  4 }{ 2.50  *  4\pi *10^{-7}  * 1000 }

=>      I_b  =  400 \ A

4 0
2 years ago
It is known that a shark can travel at a speed of 17 m/s. How far can a shark go in 8 seconds?
o-na [289]

Answer:136 m

Explanation:17*8

6 0
3 years ago
If the mass of an object is 10 Kg and it experiences a Net force of 60 Newtons. What is the acceleration?
Solnce55 [7]

Answer:

6 m/s^2

Explanation:

F = ma

60N = (10 kg)a

a = 6m/s^2

3 0
3 years ago
A man who works for a moving company is loading a box onto a moving van. He pushes a 200N box up a 5m long ramp. If he pushes wi
OlgaM077 [116]

Answer:

η = 0.667 = 66.7%

Explanation:

The efficiency of the man can be given by the following formula:

η = output/input

where,

η = efficiency of man = ?

output = potential energy gain of the box = Wh

input = work done by man = Fd

Therefore,

\eta = \frac{Wh}{Fd}

where,

W = weight of box = 200 N

h = height gained by box = 1 m

F = force exerted by man = 60 N

d = length of ramp = 5 m

Therefore,

\eta = \frac{(200\ N)(1\ m)}{(60\ N)(5\ m)}

<u>η = 0.667 = 66.7%</u>

8 0
3 years ago
Two large metal plates of area 0.88 m2 face each other, 4.8 cm apart, with equal charge magnitudes but opposite signs. The field
Nuetrik [128]

Answer:

q=6.22*10^-10C

Explanation:

Two large metal plates of area 0.88 m2 face each other, 4.8 cm apart, with equal charge magnitudes but opposite signs. The field magnitude E between them (neglect fringing) is 80 N/C. Find |q|

E=α/∈, electric field within the plate

α=q/A

A=area of the plate

∈=is the permittivity

substituting , we have

The field magnitude E between them (neglect fringing)

E=q/A∈

q=EA∈

q=0.88*80*8.84*10^-12

q=6.22*10^-10C

3 0
3 years ago
Other questions:
  • Two rowers, who can row at the same speed in still water, head across a river. . . The first rower (Alice) heads straight across
    11·1 answer
  • Who first used the zodiac constellations? Will Mark Brainliest!!!
    7·1 answer
  • Lightning is an example of what kind of electricity
    9·2 answers
  • A playground ride consists of a disk of mass M = 49 kg and radius R = 1.7 m mounted on a low-friction axle. A child of mass m =
    11·1 answer
  • Three forces are applied to an object, as shown in the diagram below. F1 = 30 N, F2 = 34 N, F3 = 20 N, d1 = 25 mm, d2 = 20 mm, d
    8·1 answer
  • A wire of radius 0.8 cm carries a current of 106 A that is uniformly distributed over its cross-sectional area. Find the magneti
    7·1 answer
  • How does surface area affect the amount of air resistance an object experiences?
    9·1 answer
  • You are standing 5 m from a loud machine. You move 10 m from the machine to help reduce the intensity of the sound. Calculate th
    15·1 answer
  • Which could most likely describe the three surfaces?
    15·2 answers
  • Waves interact with ___ and other ___.
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!