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3 years ago

A train moves east with a speed of 45 m/s. A man on the train walks west

Physics

1 answer:

miv72 [106K]3 years ago

5 0

Answer: D. 25s

Explanation:

speed = distance travelled/time taken

Or:

v = $\frac{s}{t}$

∴ t = $\frac{s}{v}$ = $\frac{10}{0.4}$ = 25s

Therefor, the answer is 25s or D.

* Hopefully this helps:) Mark me the brainliest:)!!!

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A child's top is held in place upright on a frictionless surface. The axle has a radius of ????=3.21 mm . Two strings are wrappe

tekilochka [14]

Answer:

Angular momentum, $L=6.47\times 10^{-3}\ m$

Explanation:

It is given that,

Radius of the axle, $r=3.21\ mm=3.21\times 10^{-3}\ m$

Tension acting on the top, T = 3.15 N

Time taken by the string to unwind, t = 0.32 s

We know that the rate of change of angular momentum is equal to the torque acting on the torque. The relation is given by :

$\tau=\dfrac{dL}{dt}$

Torque acting on the top is given by :

$\tau=F\times r$

Here, F is the tension acting on it. Torque acting on the top is given by :

$\tau=2F\times r$

$2T\times r=\dfrac{L}{t}$

$L=2T\times r \times t$

$L=2\times 3.15\times 3.21\times 10^{-3}\times 0.32$

$L=6.47\times 10^{-3}\ m$

So, the angular momentum acquired by the top is $6.47\times 10^{-3}\ m$ . Hence, this is the required solution.

7 0

3 years ago

In an experiment, a variable, position-dependent force FC) is exerted on a block of mass 1.0 kg that is moving on a horizontal s

marshall27 [118]

Answer:

C) The function F(x) for 0 < x < 5, the block's initial velocity, and the value of Fr.

Explanation:

Yo want to prove the following equation:

$W_N=\Delta K\\\\$

That is, the net force exerted on an object is equal to the change in the kinetic energy of the object.

The previous equation is also equal to:

$F(x)x-F_f=\frac{1}{2}m(v_f^2-v_o^2)$ (1)

m: mass of the block

vf: final velocity

v_o: initial velocity

Ff: friction force

F(x): Force

x: distance

You know the values of vf, m and x.

In order to prove the equation (1) it is necessary that you have C The function F(x) for 0 < x < 5, the block's initial velocity, and the value of F. Thus you can calculate experimentally both sides of the equation.

8 0

2 years ago

A 1500 kg truck is acted upon by a force that decreases its speed from 25 m/s to 15 m/s in 8 s. What is the magnitude of the for

Citrus2011 [14]

Answer:

F = 1,875 N

Explanation:

force=

$\frac{change \: in \: momentum}{time \: taken}$

∆H = m∆V

where ∆H ----> change in momentum.

( final momentum - initial momentum )

and ∆V ----> change in velocity

( final velocity - initial velocity )

and m ----> is mass

then f =

$\frac{1500 \times (25 - 15)}{8}$

= 1,875 N

4 0

3 years ago

In which medium does sound travel the fastest?

Vikki [24]

1. D - sound travels the fastest through solids

2. 50 mm/s - v=fa

3. B - only process that involves changing waves

4 0

3 years ago

A photon of wavelength 192 nm strikes an aluminum surface along a line perpendicular to the surface and releases a photoelectron

alex41 [277]

Answer:

$KE=3.529\times10^{−27}\ J$

Explanation:

Given that

Wavelength λ=192 nm

So energy of photon,E

$E=\dfrac{hC}{\lambda }$

Now by putting the values

$h=6.6\times 10^{-34}\ m^2.kg/s$

$C=3\times 10^{8}\ m/s$

$E=\dfrac{6.6\times 10^{-34}\times 3\times 10^{8}}{192\times 10^{-9} }$

$E=1.03\times 10^{-18} J$

We know that

Kinetic energy given as

$KE=\dfrac{P^2}{2m}$

$KE=\dfrac{E^2}{2mC^2}$

$KE=\dfrac{(1.03\times 10^{-18})^2}{2\times 1.67\times 10^{-27}(3\times 10^8)^2}$

$KE=3.529\times10^{−27}\ J$

5 0

3 years ago