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
dezoksy [38]
3 years ago
5

David rowed a boat upstream for three miles and then returned to point he started from. The entire journey took four hours. The

speed of the stream is one mile per hour. Find David's speed in still water. (Hint: speed = distance ÷ time, upstream speed = speed of the boat – speed of the stream, and downstream speed = speed of the boat + speed of the stream)
David's speed in still water is ____ miles per hour.
Physics
1 answer:
frez [133]3 years ago
4 0
Upstream speed = S - 1
Downstream speed = S + 1

Average speed = total distance / total time

Average speed = (S - 1) + (S + 1) / 2
= S

S = 6 miles / 4 hours
S = 1.5 miles per hour
You might be interested in
Which of the following are true about S waves
shusha [124]

Answer:

3. they can travel through solids

4. they move rock at right angles to the direction of wave travel

Explanation:

  • S waves are called transverse waves they have the ability to move past the solids. They cannot move through the liquids, these waves are perpendicular to the direction of travel.  
  • They are also called longitudinal waves, the ad is second to record on the seismograph as they slowly pass through the rocks. They have a speed of 3.4 to 7.2 km as per the boundary.
6 0
3 years ago
During a circus performance, a 72-kg humancannonball is shot out of an 18-m-long cannon. If thehuman cannonball spends 0.95 s in
andreyandreev [35.5K]

Answer:

2872.8 N

Explanation:

We have the following information

m =n72kg

Δy = 18m

t = 0.95s.

From here we use the equation

Δy=1/2at2 in order to solve for the acceleration.

So a

=( 2x 18m)/(0.95s²)

= 36/0.9025

= 39.9m/s2.

From there we use the equation

F = ma

F=(72kg) x (39.9)

= 2872.8N.

2872.8N is the average net force exerted on him in the barrel of the cannon.

Thank you!

7 0
3 years ago
Who was the discoverer of the neutron
Pavel [41]

Answer:

James Chadwick

Explanation:

In May 1932 James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron

6 0
2 years ago
Read 2 more answers
Learning Goal: To practice Problem-Solving Strategy 7.2 Problems Using Mechanical Energy II. The Great Sandini is a 60.0-kg circ
andreev551 [17]

Answer:

v = 15.8 m/s

Explanation:

Let's analyze the situation a little, we have a compressed spring so it has an elastic energy that will become part kinetic energy and a potential part for the man to get out of the barrel, in addition there is a friction force that they perform work against the movement.  So the variation of mechanical energy is equal to the work of the fictional force

    W_{fr} = ΔEm = Em_{f} -Em₀

Let's write the mechanical energy at each point

Initial

    Em₀ = Ke = ½ k x²

Final

   Em_{f} = K + U = ½ m v² + mg y

Let's use Hooke's law to find compression

    F = - k x

    x = -F / k

    x = 4400/1100

    x = - 4 m

Let's write the energy equation

    fr d = ½ m v² + mgy - ½ k x²

Let's clear the speed

   v² = (fr d + ½ kx² - mg y) 2 / m

   v² = (40 4.00 + ½ 1100 4² - 60.0 9.8 2.50)   2/60.0

   v² = (160 + 8800 - 1470) / 30

   v = √ (229.66)

   v = 15.8 m/s

5 0
3 years ago
Read 2 more answers
Consider f(x) = -4x2 + 24x + 3. Determine whether the function has a maximum or minimum value. Then find the
murzikaleks [220]

Answer:

The function has a maximum in x=3

The maximum is:

f(3) = 39

Explanation:

Find the first derivative of the function for the inflection point, then equal to zero and solve for x

f(x)' = -4*2x + 24=0

-4*2x + 24=0

8x=24

x=3

Now find the second derivative of the function and evaluate at x = 3.

If f (3) ''< 0 the function has a maximum

If f (3) '' >0 the function has a minimum

f(x)''= 8

Note that:

f(3)''= -8

the function has a maximum in x=3

The maximum is:

f(3)=-4(3)^2+24(3) + 3\\\\f(3) = 39

4 0
3 years ago
Other questions:
  • In general, what happens to temperature as depth below earths surface increases
    8·1 answer
  • Using the formula for work, Match the Force × Distance problems with their correct "Work Performed" answer. The first example ha
    11·1 answer
  • Which of the following is the most likely end for a star that is small to average in size?
    10·1 answer
  • Is baking soda less dense or more dense than water?
    6·1 answer
  • If it takes 600 N to move a box 5 meters, how much work is done on the box?
    9·1 answer
  • A uniform pole AB of weight 5w and length 8a is suspended horizontally by tho strings attached to it at C and D where AC=DB=a. A
    15·1 answer
  • The Pioneer 10 spacecraft was launched in March 1972 to explore the solar system. Pioneer 10 has continued on its journey and is
    8·2 answers
  • 6. Gravity formed the planets<br> -True<br> -False
    8·2 answers
  • If you increase the frequency of a sound wave four times, what will happen to its speed?
    7·1 answer
  • The acceleration of positive performing SHM is 12cm/sec at distance of 3cm from the mean position its time period is?​
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!