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
KengaRu [80]
3 years ago
8

A crew team rows a boat at a rate of 20 km/h in still water. In practice on a river, the team rows for 30 minutes up the river (

against the current), and then for 30 minutes down the river (with the current). The speed of the river current is 1.5 km/h. How much farther did they travel in the second 30 minutes?
Physics
1 answer:
sweet-ann [11.9K]3 years ago
6 0
In the second 30 mins, the speed should be 20 + 1.5 = 21.5 km/h

So S = 21.5 * 30/60 = 10.75 km
You might be interested in
When an object is at a distance of twice the focal length from a concave lens, the image produced is virtual and smaller than th
Elenna [48]
The right answer for the question that is being asked and shown above is that: "The image produced is virtual and of the same size as the object." the image if the object is shifted closer to the lens to a point one focal length away from it is that The image produced is virtual and of the same size as the object.<span>
</span>
3 0
3 years ago
Read 2 more answers
A 0.5 kg block of aluminum (caluminum=900j/kg⋅∘c) is heated to 200∘c. the block is then quickly placed in an insulated tub of co
Alex_Xolod [135]

To solve this problem, we should recall the law of conservation of energy. That is, the heat lost by the aluminium must be equal to the heat gained by the cold water. This is expressed in change in enthalpies therefore:

- ΔH aluminium = ΔH water

where ΔH = m Cp (T2 – T1)

The negative sign simply means heat is lost. Therefore we calculate for the mass of water (m):

- 0.5 (900) (20 – 200) = m (4186) (20 – 0)

m = 0.9675 kg

 

Using same mass of water and initial temperature, the final temperature T of a 1.0 kg aluminium block is:

- 1 (900) (T – 200) = 0.9675 (4186) (T – 0)

- 900 T + 180,000 = 4050 T

4950 T = 180,000

T = 36.36°C

 

The final temperature of the water and block is 36.36°C

4 0
4 years ago
Read 2 more answers
What parts are found in an electric generator? Check all that apply.
Blizzard [7]

Answer:

an armature a permanent magnet brushes slip rings

Explanation:

6 0
3 years ago
Read 2 more answers
A block has a volume of 0.09 m3 and a density of 4,000 kg/m3. What's the force of gravity acting on the block in water?
12345 [234]

                                       Density = (mass) / (volume)

                                4,000 kg/m³ = (mass) / (0.09 m³)

Multiply each side
by  0.09 m³ :           (4,000 kg/m³) x (0.09 m³) = mass

                                 mass = 360 kg .

Force of gravity = (mass) x (acceleration of gravity)

                           = (360 kg) x (9.8 m/s²)

                           = (360 x 9.8)  kg-m/s²

                           =   3,528 newtons . 

That's the force of gravity on this block, and it doesn't matter
what else is around it.  It could be in a box on the shelf or at
the bottom of a swimming pool . . . it's weight is 3,528 newtons
(about 793.7 pounds).

Now, it won't seem that heavy when it's in the water, because
there's another force acting on it in the upward direction, against
gravity.  That's the buoyant force due to the displaced water.

The block is displacing 0.09 m³ of water.  Water has 1,000 kg of
mass in a m³, so the block displaces 90 kg of water.  The weight
of that water is  (90) x (9.8) = 882 newtons (about 198.4 pounds),
and that force tries to hold the block up, against gravity.

So while it's in the water, the block seems to weigh

       (3,528  -  882) = 2,646 newtons  (about 595.2 pounds) .

But again ... it's not correct to call that the "force of gravity acting
on the block in water".  The force of gravity doesn't change, but
there's another force, working against gravity, in the water.
5 0
3 years ago
Read 2 more answers
Which statement about subatomic particles is true?
navik [9.2K]

A. An electron has far less mass than either a proton or neutron.

4 0
3 years ago
Other questions:
  • Which has more thermal energy, a 5-kg bowling all that has been resting on a hot driveway for 4 hours on a 350C day, or the same
    6·2 answers
  • The current world-record motorcycle jump is 77.0 m, set by Jason Renie. Assume that he left the take-off ramp at 11.0° to the ho
    15·1 answer
  • An electron has _____
    9·2 answers
  • can you please help me i will follow you or i will give brainliest please help me with this question.​
    14·2 answers
  • White light viewed through a prism is an example of a(n) _______________ spectrum.
    10·1 answer
  • You are trying to overhear a juicy conversation, but from your distance of 25.0 m , it sounds like only an average whisper of 20
    13·1 answer
  • A small car and an SUV are at a stoplight. The car has a mass equal to half that of the SUV, and the SUV's engine can produce a
    14·1 answer
  • 1) Consider an electric power transmission line that carries a constant electric current of i = 500 A. The cylindrical copper ca
    12·1 answer
  • Although 0 dB is often referred to as the lower threshold of human hearing, it is important to realize that the human ear is not
    10·1 answer
  • Which characteristics describe whether a cell contains a nucleus?.
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!