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
ICE Princess25 [194]
3 years ago
9

44. A rescue helicopter is hovering over a person whose boat has sunk. One of the rescuers throws a life preserver straight down

to the victim with an initial velocity of 1.40 m/s and observes that it takes 1.8 s to reach the water. (a) List the knowns in this problem. (b) How high above the water was the preserver released? Note that the downdraft of the helicopter reduces the effects of air resistance on the falling life preserver, so that an acceleration equal to that of gravity is reasonable.
Physics
1 answer:
Vladimir [108]3 years ago
8 0

Answer:

18.4 m

Explanation:

(a)

The known variables in this problem are:

u = 1.40 m/s is the initial vertical velocity (we take downward direction as positive direction)

t = 1.8 s is the duration of the fall

a = g = 9.8 m/s^2 is the acceleration due to gravity

(b)

The vertical distance covered by the life preserver is given by

d=ut + \frac{1}{2}at^2

If we substitute all the values listed in part (a), we find

d=(1.40 m/s)(1.8 s)+\frac{1}{2}(9.8 m/s^2)(1.8 s)^2=18.4m

You might be interested in
One speaker generates sound waves with amplitude A.
raketka [301]

Answer:

iv) It is 9x bigger than before

Explanation:

As the amplitudes of the new speakers add directly with the original one, taking into account the phase that they have, the composed amplitude of the sound wave is as follows:

At = A + 4A -2A = 3 A

The intensity of the wave, assuming it propagates evenly in all directions, is constant at a given distance from the source, and can be expressed as follows:

I = P/A

where P= Power of the wave source, A= Area (for a point source, is equal to the surface area of a sphere of radius r, where is r is the distance to the source along a straight line)

For a sinusoidal wave, the power is proportional to the square of the amplitude, so the intensity is proportional to the square of the amplitude also.

If the amplitude changes increasing three times, the change in intensity will be proportional to the square of the change in amplitude, i.e., it will be 9 times bigger.

So, the statement iv) is the right one.

7 0
3 years ago
A car travel with a constant velocity of 20.5m/s for 20seconds what distance does it cover in this time ?​
prohojiy [21]

Answer:

410 m

Explanation:

Given:

v₀ = 20.5 m/s

a = 0 m/s²

t = 20 s

Find: Δx

Δx = v₀ t + ½ at²

Δx = (20.5 m/s) (20 s) + ½ (0 m/s²) (20 s)²

Δx = 410 m

8 0
3 years ago
The vertical component of the projectile motion of an object depends on which of these? initial velocity or angel of trajectory
SVEN [57.7K]
It depends on both of them.

In fact, the projectile begins its motion with an initial velocity of v_0 and an angle of \alpha. On the y-axis (vertical direction), it is an accelerated motion with acceleration equal to -g (gravitational acceleration). The vertical velocity of the projectile at any time t is given by
v_y (t) = v_0 sin \alpha + gt
and as it can be seen, this depends on both initial velocity and angle.
3 0
3 years ago
An object that is moving must have a change in A) its speed. B) its position. C) its acceleration. D) its applied force.
denis-greek [22]

An object that's moving doesn't necessarily change its speed or acceleration. Also, the force applied to it doesn't need to change ... in fact, a moving object doesn't need ANY force applied to it in order to keep moving.

But any moving object WILL have a change in its position ... THAT's how you know it's moving, and that's WHY you say "It's moving !". (choice-B)

8 0
3 years ago
What’s the potential difference across a 5.0 ohms resistor that carries a current of 5.0A
vivado [14]

Answer:

The correct answer is B-25 V

Explanation:

We apply Ohm's Law, according to which:

V = i x R

V = 5A x 5Ω

V= 25 V

Being V the potential difference whose unit is the VOLT, i the current intensity (Ampere) and R the electrical resistance (ohm)

3 0
3 years ago
Other questions:
  • Is the force of gravity stronger on a piece of crumpled paper or a normal piece of flat paper?
    8·1 answer
  • Which of the following would probably not work with circuits on a daily basis
    7·1 answer
  • To ensure the greatest nutritional benefits, dietary guidelines suggest which of the following?
    10·2 answers
  • How did world cup soccer become cool?
    5·1 answer
  • When determining a region's climate, the two main variables considered are the average what? ( They don't have the subject "Scie
    11·1 answer
  • NEED HELP ASAP!!!!!!!!!!!!!
    14·2 answers
  • HELP!!
    5·1 answer
  • An astronaut whose mass is 80 kg carries an empty oxygen tank with a mass of 10 kg. The astronaut throws the tank away with a sp
    11·1 answer
  • I need it in the next hour or so!
    9·1 answer
  • What conclusion can be made about the relationship between the wavelength of light and the angle of refraction?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!