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3 years ago

Conservation of momentum

Physics

1 answer:

deff fn [24]3 years ago

5 0

Answer: 6.21 m/s opposite to Janet

Explanation:

Given

mass of Janet $m_j=59\ kg$

mass of Sarah $m_s=32\ kg$

The initial velocity of Janet $u_1=7\ m/s$

The final velocity of Janet after the collision is $v_1=2\ m/s$

the final velocity of Sarah after the collision is $v_2=3\ m/s$

Conserving linear momentum

$\Rightarrow m_ju_1+m_su_2=m_jv_1+m_sv_2\\\Rightarrow 59\times 7+32\times u_2=59\times 2+32\times 3\\\Rightarrow 32u_2=118+96-413\\\Rightarrow u_2=\frac{-199}{32}=-6.21\ m/s$

Negative indicates the direction of velocity is opposite than of Janet

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A uniform rod is 2. 0 m long and has mass 15 kg. What is most nearly the rod's mass moment of inertia?

trapecia [35]

The rod's mass moment of inertia is 5kgm².

<h3>Moment of Inertia:</h3>

The "sum of the product of mass" of each particle with the "square of its distance from the axis of rotation" is the formula for the moment of inertia.

The Parallel axis Theorem can be used to compute the moment of inertia about the end of the rod directly or to derive it from the center of mass expression. I = kg m². We can use the equation for I of a cylinder around its end if the thickness is not insignificant.

If we look at the rod we can assume that it is uniform. Therefore the linear density will remain constant and we have;

or = M / L = dm / dl

dm = (M / L) dl

$I = \int\limits^M_0 {r^2} \, dm$

$I = \int\limits^\frac{L}{2} _\frac{-L}{2} {I^2 (M/L)} \, dl$

Here the variable of the integration is the length (dl). The limits have changed from M to the required fraction of L.

$I = \int\limits^\frac{L}{2} _\frac{-L}{2} {I^2 (M/L)} \, dl$

$I = \frac{M}3L}[(\frac{L^3}{2^3} - \frac{-L^3}{2^3} )]\\\\I = \frac{1}{12}ML^2$

Mass of the rod = 15 kg

Length of the rod = 2.0 m

Moment of Inertia, I = $\frac{1}{12}15 (2)^2$

= 5 kgm²

Therefore, the moment of inertia is 5kgm².

Learn more about moment of inertia here:

brainly.com/question/14119750

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4 0

2 years ago

What are light years actually? answer in brief

a_sh-v [17]

A light year is a distance.
It's the distance that light travels in a year, through vacuum.
The distance is about 5.875 trillion miles.
The nearest star outside our solar system is about 4.2 light years from us.

Sorry to have rambled on for so long.

6 0

3 years ago

A small rock is thrown vertically upward with a speed of 27.0 m/s from the edge of the roof of a 21.0-m-tall building. The rock

lbvjy [14]

Answer:

A. 33.77 m/s

B. 6.20 s

Explanation:

Frame of reference:

Gravity g=-9.8 m/s^2; Initial position (roof) y=0; Final Position street y= -21 m

Initial velocity upwards v= 27 m/s

Part A. Using kinematics expression for velocities and distance: