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
e-lub [12.9K]
3 years ago
9

How long does it take for a dropped rock to fall from a height of 8 meters

Physics
1 answer:
seropon [69]3 years ago
5 0

Answer:

1.28 s

Explanation:

Given:

Δy = 8 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: t

Δy = v₀ t + ½ at²

(8 m) = (0 m/s) t + ½ (9.8 m/s²) t²

t = 1.28 s

You might be interested in
A block with mass of 10 kg is on a frictionless surface. One hand on the left side of the block is pushing it to the right. A se
igomit [66]

Answer:

W_2=-12J

Explanation:

The work of force 2 will be given by the vectorial equation W_2=F_2.d. We know the value of F_1 and have information about its movement, which relates to the net force F=F_1+F_2.

About this movement we can obtain the acceleration using the equation v_f^2=v_i^2+2ad. Since it departs from rest we have a=\frac{v_f^2}{2d}.

And then using Newton's 2dn Law we can obtain the net force F=ma, thus we will have F_2=F-F_1=ma-F1=\frac{mv_f^2}{2d}-F_1

And we had the work done by force 2 as:

W_2=F_2.d=\frac{mv_f^2}{2}-F_1d

(The sign will be given algebraically since we take positive the direction to the right.)

With our values:

W_2=\frac{(10kg)(2m/s)^2}{2}-(8N)(4m)=-12J

<em>Another (shorter but maybe less intuitive way for someone who is learning) way of doing this would have been to say that the work done by both forces would be equal to the variation of kinetic energy:</em>

<em>W_1+W_2=K_f-K_i=K_f=\frac{mv_f^2}{2}</em>

<em>Which leads us to the previous equation straightforwardly.</em>

6 0
3 years ago
PLEASE HELP ME I AM TIMED!
Leno4ka [110]

Answer:

Well my good friend the other person did not give U a good answer, it is actually the third one

Explanation: well it is the most logical of all the answers if you think about it and a lot of the creatures we have in the water today are thought of to have once lived on land based on the fossils we still find to this very day my friend

3 0
3 years ago
Traveling 221 miles from Boston Back Bay Station to NYC Penn Station takes 3 hours
Nostrana [21]

Answer:

Approximately 116\; \text{miles} for the train from Boston to NYC Penn Station.

Approximately 105\; \text{miles} for the train from NYC Penn Station to Boston.

Explanation:

Convert minutes to hours:

\begin{aligned}t(\text{BOS $\to$ NYC}) &= 3\; {\text{hour}} + 40\; \text{minute} \times \frac{1\; {\text{hour}}}{60\; \text{minute}} \\ &=\left(3 + \frac{2}{3}\right)\; \text{hour}\\ &= \frac{11}{3}\; \text{hour} \end{aligned}.

\begin{aligned}t(\text{NYC $\to$ BOS}) &= 4\; {\text{hour}} + 5\; \text{minute} \times \frac{1\; {\text{hour}}}{60\; \text{minute}} \\ &= \frac{49}{15}\; \text{hour} \end{aligned}.

Calculate average speed of each train:

\begin{aligned}v(\text{BOS $\to$ NYC}) &= \frac{s}{t}\\ &= \frac{221\; \text{mile}}{\displaystyle \frac{11}{3}\; \text{hour}} \\ &= \frac{663}{11}\; \text{mile} \cdot \text{hour}^{-1}\end{aligned}.

\begin{aligned}v(\text{NYC $\to$ BOS}) &= \frac{s}{t}\\ &= \frac{221\; \text{mile}}{\displaystyle \frac{49}{15}\; \text{hour}} \\ &= \frac{2652}{49}\; \text{mile} \cdot \text{hour}^{-1}\end{aligned}

Assume that it takes a time period of t for the trains to pass by each other after departure. Distance each train travelled would be:

s(\text{NYC $\to$ BOS}) = v(\text{NYC $\to$ BOS})\, t.

s(\text{BOS $\to$ NYC}) = v(\text{BOS $\to$ NYC})\, t.

Since the trains have just passed by each other, the sum of the two distances should be equal to the distance between the stations:

v(\text{NYC $\to$ BOS})\, t + v(\text{BOS $\to$ NYC})\, t = 221\; \text{mile}.

Rearrange and solve for t:

(v(\text{NYC $\to$ BOS}) + v(\text{BOS $\to$ NYC}))\, t = 221\; \text{mile}.

\begin{aligned}t &= \frac{221\; \text{mile}}{v(\text{NYC $\to$ BOS}) + v(\text{BOS $\to$ NYC})} \\ &= \frac{221\; \text{mile}}{\displaystyle \frac{663}{11}\; \text{mile} \cdot \text{hour}^{-1} + \frac{2652}{49}\; \text{mile} \cdot \text{hour}^{-1}} \\ &= \frac{539}{279}\; \text{hour}\end{aligned}.

Distance each train travelled in t = (539 / 279)\; \text{hour}:

\begin{aligned}s(\text{BOS $\to$ NYC}) &= v\, t \\ &= \frac{663}{11}\; \text{mile} \cdot \text{hour}^{-1} \times \frac{539}{279}\; \text{hour} \\ &\approx 116\; \text{mile}\end{aligned}.

\begin{aligned}s(\text{NYC $\to$ BOS}) &= v\, t \\ &= \frac{2652}{49}\; \text{mile} \cdot \text{hour}^{-1} \times \frac{539}{279}\; \text{hour} \\ &\approx 105\; \text{mile} \end{aligned}.

8 0
2 years ago
When you blow some air above a paper strip, the paper, rises. This is because 1.) the air above the paper moves faster and the p
wlad13 [49]

This is happened because "the air" above "moves faster" and "the pressure" is "lower" .

Option:  1

<u>Explanation</u>:

Air movement take place from the region where air pressure is more than the region where the pressure is low. When we "blow" air above the "paper strip" paper rises because "low pressure" is created above the strip as high speed winds always travel with reduced air pressure. Hence due to higher air pressure below the strip, it is pushed upwards. This difference in pressure results into fast air moves. This happen because "speed" of the wind depends on "the difference between the pressures" of the air in the two regions.

8 0
4 years ago
which statement is true about the atomic mass? a. it is never greater than the atomic number b. it always equal the atomic numbe
Shtirlitz [24]
D. it can be greater than the atomic number
5 0
3 years ago
Read 2 more answers
Other questions:
  • The diver has least gravitational potentail engery at position
    15·1 answer
  • A cyclist is riding his bike up a mountain trail. When he starts up the trail, he is going 8 m/s. As the trail gets steeper,he s
    6·1 answer
  • If you were asked which type of power, generated from a non-renewable resource, has the least negative effect on the environment
    6·1 answer
  • A wave with a period of 1⁄3 second has a frequency of A. 67 Hz. B. 33 Hz. C. 300 Hz. D. 3 Hz.
    13·1 answer
  • 2. When temperature increases, what happens to the molecules in a chemical reaction?
    11·1 answer
  • A boy and his skateboard have a combined mass of 65 kg what is the speed of the boy and skateboard if they have a momentum of 27
    15·1 answer
  • Which element has a full valence shell of electrons
    13·1 answer
  • An object is placed near a plane mirror. What must be true about the image if the image distance is negative?
    12·1 answer
  • Please helppppp ASAP mark you Brainliest
    12·1 answer
  • A wax is applied to the bottom surface of cross country skis to achieve a good balance between traction when
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!