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3 years ago

8

A skydiver jumps from an airplane and falls freely for 5 seconds. If the sky diver's velocity increases by 49 m/s during that ti

me, at which rate is the diver accelerating ?

2 answers:

Sergeeva-Olga [200]3 years ago

8 0

Acceleration = (change in speed) / (time for the change)

   =    (49 m/s) / (5 seconds)

   = (49 / 5) m/s / s

   =    9.8 m/s²

mihalych1998 [28]3 years ago

3 0

Your answer would be 9.8

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An arrow, starting from rest, leaves the bow with a speed of25

xz_007 [3.2K]

Answer:

The speed will be $v_f= 43.30 \frac{m}{s}$

Explanation:

We can use the following kinematics equation

$v_f^2-v_i^2=2 \ a \ d$

where $v_f$ is the final speed, $v_i$ its the initial speed, a is the acceleration, and d the distance.

The force will be tripled, the force is:

$\vec{F} = m \vec{a}$

in 1D

$F = m a$

Now, for the original problem, we have

$(25 \frac{m}{s})^2-(0 \frac{m}{s})^2=2 \ a' \ d'$

$(25 \frac{m}{s}))^2=2 \ a' \ d'$

$625 \frac{m^2}{s^2}=2 \ a' \ d'$

For the second problem, we have

$(v_f})^2-(v_i)^2=2 \ a'' \ d''$

starting from the rest, we have the same initial velocity.

$(v_f})^2-(0\frac{m}{s})^2=2 \ a'' \ d''$

$(v_f})^2=2 \ a'' \ d''$

As the force is tripled, we have:

$F'' = 3 F'$

$m'' \ a'' = 3 m' \ a'$

But the mass its the same, so

$m' \ a'' = 3 m' \ a'$

$a'' = 3 \ a'$

So the acceleration its also tripled.

$(v_f})^2=2 \ (3 * a') \ d''$

$(v_f})^2=3 ( 2 \ ( a' \ d'' )$

As the distance traveled by the arrow must also be the same, we have:

$(v_f})^2=3 ( 2 \ ( a' \ d' )$

$(v_f})^2=3 (625 \frac{m^2}{s^2})$

$v_f= \ sqrt{3 (625 \frac{m^2}{s^2})}$

$v_f= \ sqrt{3} 25 \frac{m}{s}$

$v_f= 43.30 \frac{m}{s}$

And this will be the speed from the arrow leaving the bow.

5 0

3 years ago

Why does the frequency of a wave increase as the wavelength decreases? A) because the wave speed remains constant B) because the

amid [387]

Answer:

A) because wave speed remains constant.

Explanation:

The wave speed of a wave in a medium depends on the nature of the medium.

For transverse waves in a string given by,

$v = \sqrt{\frac{T}{m}}$ , T = tension , m = linear density

For longitudinal waves in a solid,

$v = \sqrt{\frac{ξ}{ρ}}$ , ξ = modulus of elasticity, ρ = density

Like wise for different media, different properties and parameters govern the speed of waves moving through them.

It is important to mind in v = fλ ,f or λ does not influence on speed of wave in a medium but shows how f and λ varies as a wave propagate in a medium(/media).

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3 years ago

Read 2 more answers

A rifle that shoots bullets at 471 m/s is to be aimed at a target 46.4 m away. If the center of the target is level with the rif

Genrish500 [490]

Answer:

The equation that will express this result os

h = 0 = vy t - 1/2 g t^2 so the net height traveled by the bullet is zero

vy t = 1/2 g t^2

vy = 1/2 g t

vy = 1/2 * 9.8 * t you could use -9.8 to indicate vy and g are in different directions

tx = sx/ vx = 46.4 / 471 = .0985 sec time to travel up and down to original height

th = .0985 / 2 = .0493 sec time to reach maximum height

vy = g ty = 9.8 * .0493 sec = .483 m/s initial vertical speed

Sy = vy t - 1/2 g t^2 = .483 * .0493 - 1.2 9.8 (.0493^^2)

Sy = .0238 - 4.9 ( .0493)^2 = .0238 - .0119 = .0119 m

Height to which bullet will rise - if the gun is aimed at this height then in .0985 seconds the bullet will fall to zero height

Check: .483 / 9.8 = .0493 time to reach zero vertical speed

total travel time = 2 * .0493 = .0986 sec

471 * .0986 = 46.4 m total distance traveled by bullet

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2 years ago

When temperature increases the kinetic energy of the particles in a material, true or false?

saul85 [17]

Answer:

True

Explanation:

kinetic energy is proportional to temperature

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3 years ago

Two objects were lifted by a machine.One object had a mass of 2 kilograms and was lifted at a speed of 2 m/sec.The other had a m

NikAS [45]

Answer:

While lifting two object the machine needs the different momentum for different mass object.

Explanation:

Momentum is the quantity of motion contained in an object. Usually it is measured by the product of mass and velocity.
Momentum of first mass = 2 kg × 2 m/sec = 4 kg m/sec
Momentum of second mass = 4 kg × 3 m/sec = 12 kg m/sec
So the machine requires higher mass in motion for second object ( i.e. momentum) than the first one while lifting.

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3 years ago