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3 years ago

If you jump off a 7 m diving platform, how long will it take you to hit the

Physics

1 answer:

Allushta [10]3 years ago

3 0

Answer:

C.) T = 1.20s

Explanation:

From equation of motion,

S = ut + ½gt²

S = 7m

g = 9.8m/s²

U = 0m/s (since he starts from rest)

t = ?

S = ut + ½gt²

7 = 0 * t + ½ * 9.8 * t²

7 = 0 + 4.9t²

t² = 7 / 4.9

t² = 1.42857

t = √(1.42857)

t = 1.195s

t = 1.20s

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So we were working on some pulley problems but this one has kinda left me scratching my head, please help! My question is for pa

USPshnik [31]

Explanation:

Sum of forces on B in the -y direction:

∑F = ma

mBg − T = mBa

Sum of forces on A in the +x direction:

∑F = ma

T = mAa

Substitute:

mBg − mAa = mBa

mBg − mBa = mAa

mA = mB (g − a) / a

Plug in values:

mA = (5 kg) (10 m/s² − 0.01 (10 m/s²)) / (0.01 (10 m/s²))

mA = 495 kg

The answer key seems to have a mistake. It's possible they meant mB = 1 kg, or they changed mB to 5 kg but forgot to change the answer.

8 0

3 years ago

Light of a given wavelength is used to illuminate the surfacce of a metal, however, no photoelectrons are emitted. In order to c

Jlenok [28]

Answer:

B. use light of a shorter wavelength.

Explanation:

We know that

$E= \frac{hc}{\lambda}$

h= plank's constant

c= speed of light

λ= wavelength of the incident light

so, in order to have sufficient energy for for the emission of electron, the incident's radiation must have λ small enough.

B. use light of a shorter wavelength.

6 0

3 years ago

For a constant force the impulse could be increased by

Aleksandr [31]

For constant fore the impulse could be increased by increasing the time for the force.

5 0

3 years ago

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What is the medium the energy in the slinky wave travels through?

vlabodo [156]

Answer:

The metal coil of the slinky

Explanation:

The wave travels on the actual slinky which we see deforming as the wave goes through.

6 0

3 years ago

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A dock worker loading crates on a ship finds that a 27 kg crate, initially at rest on a horizontal surface, requires a 80 N hori

Aleksandr-060686 [28]

Answer:0.302

Explanation:

Given

mass of crate m=27 kg

Force required to set crate in motion is 80 N

Once the crate is set in motion 56 N is require to move it with constant velocity

i.e. 80 N is the amount of force needed to just overcome static friction and 56 is the kinetic friction force

thus

$f_s(static\ friction)=\mu \cdot N$

where $\mu$ is the coefficient of static friction and N is Normal reaction

$N=mg$

$f_s=\mu mg$

$\mu mg=80$

$\mu =\frac{80}{27\times 9.8}$

$\mu =0.302$

7 0

4 years ago