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3 years ago

Has scientific knowledge changed over time?

Physics

1 answer:

marusya05 [52]3 years ago

3 0

Yes, as new discoveries have been made the body of scientific knowledge has changed

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What is the resistance if the current is 15 amps and the voltage 105 volts

Ludmilka [50]

I think it’s R=U/I = 120/5 = 24

3 0

3 years ago

A boulder released by a rockslide rolls 60 m in 4 s. What is its average speed?

Gelneren [198K]

Answer:

15 m per second

900m per minute

54,000 per hour

Explanation:

60 divided by 4 to get per second then times 60 for per minutes

then times 60 to get per hour

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3 years ago

Degeneracy pressure stops the crush of gravity in all the following except

quester [9]

Answer:

A very massive main- sequence star

Explanation:

Degeneracy pressure refers to pressure expend by dense material , which is composed of fermions, which is an example of electrons in a white dwarf star. According to Pauli exclusion principle, which states that no two fermions can exist in the same quantum state, actually give details about the pressure.

When there is stellar masses that is less than about 1.44 of that of solar masses, there will be gravitational fall in the energy , and the energy will not be sufficient to produce the neutrons of a neutron star, therefore, the fall is abstruptly stopped through the electron degeneracy to form white dwarfs.this result to the creation of an effective pressure that further prevents gravitational fall.

5 0

3 years ago

FIGURE 2 shows a constant force, F of magnitude 20N pulled a light cord wrapped around a pulley to lift a bucket of mass 1.53kg.

slava [35]

(a) $14.3 rad/s^2$

The angular acceleration of the pulley can be found by using the equivalent of Newton's second law for rotational motions:

$\tau = I \alpha$ (1)

where

$\tau$ is the net torque on the pulley

$I=0.385 kg m^2$ is the moment of inertia of the pulley

$\alpha$ is the angular acceleration

First, we need to find the net torque. The torque exerted by the force F (forward) is:

$\tau_t = F r = (20 N)(0.330 m)=6.6 Nm$

While the frictional torque (backward) is $\tau_f = 1.1 Nm$ . So, the net torque is

$\tau = \tau_t - \tau_f=6.6 - 1.1 = 5.5 Nm$

Now, re-arranging eq.(1), we find the angular acceleration:

$\alpha = \frac{\tau}{I}=\frac{5.5}{0.385}=14.3 rad/s^2$

(b) $4.72 m/s^2$

Assuming that the string holding the bucket is inextensible, the bucket should have the same linear acceleration of a point on the edge of the pulley, which is given by

$a= \alpha r$