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tamaranim1 [39]
3 years ago
8

A 20 kg box has an initial velocity of 2 m/s starting at the bottom of a 30-degree inclined plane. A person pushes on the box di

rectly up the frictionless inclined plane so that it travels up the inclined plane at a constant velocity of 2 m/s. Calculate the how much is done by the person after 5 seconds have past.
Physics
1 answer:
Mice21 [21]3 years ago
5 0

Answer:

Explanation:

The box is moving with constant velocity so acceleration of box is zero . That means net force on the box is zero .

The weight component acting on box parallel to incline plane

= mg sin 30⁰ = 20 x 9.8 x sin 30 = 98 N

This force is acting down the plane , hence to make the net force zero acting on box , force exerted by person will also be 98 N up the incline .

Force exerted by person = 98 N

distance travelled in 5 s

= velocity x time

= 2 x 5 = 10 m

Work done by person

= 98 x 10

= 980 J .

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If you were to drop a rock from a tall building, assuming that it had not yet hit the ground, and neglecting air resistance, aft
elena-14-01-66 [18.8K]

Since the object is dropped from some height so its initial speed must be zero

acceleration of the object is due to gravity

so we can use kinematics to find the time it will take to drop by x = 22 m

\delta x = v_i * t + \frac{1}{2}at^2

22 = 0 + \frac{1}{2}*9.8*t^2

t = 2.12 s

Now the speed after 2.12 s will be given as

v_f = v_i + at

v_f = 0 + 9.8 * 2.12

v_f = 20.8 m/s

so above is the speed and time

5 0
3 years ago
wo kids are on a seesaw. The one on the left has a mass of 75 kg and is sitting 1.5 m from the pivot point. The one on the right
Anastaziya [24]

Answer:

4.5 Nm (Anticlockwise)

Explanation:

Let the 75 kg kid is sitting at the left end and the 60 kg kid is sitting on the right end.

Anticlockwise Torque = 75 x 1.5 = 112.5 Nm

clockwise Torque = 60 x 1.8 = 108 Nm

Net torque = Anticlockwise torque - clockwise torque

Net Torque = 112.5 - 108 = 4.5 Nm (Anticlockwise)

5 0
3 years ago
After an eye examination, you put some eyedrops on your sensitive eyes. The cornea (the front part of the eye) has an index of r
mina [271]

Answer:

t = 103.45 n m

Explanation:

given,

refractive index of cornea = 1.38

refractive index of eye drop = 1.45

wavelength of refractive index = 600 nm

refractive index of eye drop is greater than refractive index of cornea and the air.

Formula used in this case

for constructive interference

2 n t = (m + \dfrac{1}{2})\lambda

At m = 0 for the minimum thickness, so

2\times 1.45 \times t = (0 + 0.5)\times 600

2.9 \times t =300

t =\dfrac{300}{2.9}

t = 103.45 n m

the minimum thickness of the film of eyedrops t = 103.45 n m

6 0
3 years ago
In a crash or collision, why is it advantageous for an occupant to extend the time during which the collision is taking place?
Veseljchak [2.6K]

Answer:

Explanation:

During a car collision momentum of vehicle ceases within a fraction of seconds so Force due to the impulse is huge.

Impulse is defined as the product of average force and time. If we can increase the period of collision for the same impulse then the average force imparted will be less.

If we can increase the time period then damage due to collision will be less.

                     

3 0
3 years ago
The X-ray source Cygnus X-1 has a mass of at least 11 solar masses and a diameter of only about one-quarter the diameter of the
SOVA2 [1]

Answer:

Answer is It was deduced from the rate at which it glimmers.

Refer below.

Explanation:

The X-ray source Cygnus X-1 has a mass of at least 11 solar masses and a diameter of only about one-quarter the diameter of the Earth. With such a small diameter it must be a compact object, and with such a large mass it can't be a white dwarf or a neutron star, so a black hole is the only possibility remaining. The diameter of Cygnus X-1 found:

It was deduced from the rate at which it glimmers.

7 0
3 years ago
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