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
Novay_Z [31]
3 years ago
8

Who was the first known contributor to the atomic theory? Select one: a. Thomson b. Bohr c. Dalton d. Democritus

Physics
1 answer:
ser-zykov [4K]3 years ago
6 0
It would be D Democritus
He contributed in around 460-370 BC
Whereas the others contributed much later from around 1700's - 1900's
You might be interested in
For work to be done on an object,
djverab [1.8K]

Answer:B

Explanation:

For work to be done, the object must move some distance as a result of a force

3 0
3 years ago
You are traveling at 14 m/s for 20 seconds. What is your displacement?
enyata [817]

Velocity = 14 m/s

Time = 20 s

Displacement = Velocity×Time = (14×20) m = 280 m

The displacement is 280 m towards the direction of motion.

5 0
3 years ago
Read 2 more answers
A 250 kg car has 6875 kg•m/s of momentum. What is it’s velocity?
liraira [26]

Answer:

v = 27.5 m/s

Explanation:

p = m × v

6,875 = 250 × v

250v = 6,875

v = 6,875/250

v = 27.5 m/s

5 0
3 years ago
A helicopter lifts a 72 kg astronaut 15 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/
NemiM [27]

Answer:

a) F_H=776.952\ N

b) F_g=706.32\ N

c) v=5.4249\ m.s^{-1}

d) KE=1059.48\ J

Explanation:

Given:

  • mass of the astronaut, m=72\ kg
  • vertical displacement of the astronaut, h=15\ m
  • acceleration of the astronaut while the lift, a=\frac{g}{10} =0.981\ m.s^{-2}

a)

<u>Now the force of lift by the helicopter:</u>

Here the lift force is the resultant of the force of gravity being overcome by the force of helicopter.

F_H-F_g=m.a

where:

  • F_H= force by the helicopter
  • F_g= force of gravity

F_H=72\times 0.981+72\times9.81

F_H=776.952\ N

b)

The gravitational force on the astronaut:

F_g=m.g

F_g=72\times 9.81

F_g=706.32\ N

d)

Since the astronaut has been picked from an ocean we assume her initial velocity to be zero, u=0\ m.s^{-1}

using equation of motion:

v^2=u^2+2a.h

v^2=0^2+2\times 0.981\times 15

v=5.4249\ m.s^{-1}

c)

Hence the kinetic energy:

KE=\frac{1}{2} m.v^2

KE=0.5\times 72\times 5.4249^2

KE=1059.48\ J

8 0
3 years ago
Read 2 more answers
Hiaaa I need help pwease" concerning the planetary orbits why was Copernicus somewhat inaccurate?"
Yuki888 [10]
Copernicus's heliocentric theory stated that the planets orbited in perfectly circular orbits. In reality, they are shaped like ellipses (ovals).
4 0
3 years ago
Other questions:
  • What do the subscript in the formula for ethane repersent
    9·1 answer
  • Read the sentence.
    8·2 answers
  • Can black wholes be an exit to the universe,why or why not? (just curious).
    15·2 answers
  • A hammer falls off the top roof and strikes the ground with a certain kinetic energy. If it fell from a roof twice as tall how w
    10·2 answers
  • Approximately what percentage of incoming solar radiation is absorbed by the oceans and continents
    11·1 answer
  • Which lenses are convex? Check all that apply. 1 2 3 4 5 6
    10·2 answers
  • Which of the following weather conditions would result in the greatest rate of evaporation from the Earth's surface? A. hot and
    11·1 answer
  • Which method of heat transfer transmits heat from the lower layers of air to the upper layers of air as the lower layers of air
    13·2 answers
  • A cabbie is trying to stop when he notices a fare is whistling them over. The
    12·1 answer
  • Eva Baul throws a ball upward at 23.4 m/s
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!