1. For each situation, determine the net force acting upon the object.

If a woman runs 100 meters north and then 70 meters south, what is her total displacement?

Burka [1]

Displacement is the distance between the starting and ending points, in the direction from the starting point to the ending point, all regardless of the route followed from the starting point to the end point.

The woman's displacement is therefore 30 meters north.

8 0

3 years ago

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How does the Wikileaks scenario show the negative power of the media?

lesya [120]

Answer:

B. The media released popular information.

Explanation:

We do not share the power in our media.

7 0

3 years ago

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Two metal disks, one with radius R1 = 2.45 cm and mass M1 = 0.900 kg and the other with radius R2 = 5.00 cm and mass M2 = 1.60 k

larisa86 [58]

Answer:

part (a) $a_1\ =\ 2.9\ kg$

Part (b) $a_2\ =\ 6.25\ kg$

Explanation:

Given,

Mass of the larger disk = $M_2\ =\ 1.60\ kg$
Mass of the smaller disk = $M_1\ =\ 0.900\ kg$
Radius of the larger disk = $R_2\ =\ 5.00\ cm\ =\ 0.05\ m$
Radius of the smaller disk = $R_1\ =\ 2.45\ cm\ =\ 0.0245\ m$
Mass of the block = M = 1.60 kg

Both the disks are welded together, therefore total moment of inertia of the both disks are the summation of the individual moment of inertia of the disks.

$\therefore I\ =\ I_1\ +\ I_2\\\Rightarrow I\ =\ \dfrac{1}{2}M_1R_1^2\ +\ \dfrac{1}{2}M_2R_2^2\\\Rightarrow I\ =\ \dfrac{1}{2} (0.9\times 0.0245^2\ +\ 1.60\times 0.05^2)\\\Rightarrow I\ =\ 2.27\times 10^{-3}\ kgm^2$

part (a)

Given that a block of mass m which is hanging with the smaller disk,

Let 'T' be 'a' be the tension in the string and acceleration of the block.

From the free body diagram of the smaller block,

$mg\ -\ T\ =\ ma\\\Rightarrow T\ =\ mg\ -\ ma\,\,\,\,eqn (1)$

From the pulley,

$\sum \tau\ =\ I\alpha\\\Rightarow T\times R_1\ =\ I\alpha\ =\ \dfrac{Ia}{R_1}\\\Rightarrow T\ =\ \dfrac{I\alpha}{R_1^2}\,\,\,eqn(2)$

From the equation (1) and (2),

$mg\ -\ ma\ =\ \dfrac{Ia}{R_1^2}\\\Rightarrow a\ =\ \dfrac{mg}{\dfrac{I}{R_1^2}\ +\ m}\\\Rightarrow a\ =\ \dfrac{1.60\times 9.81}{\dfrac{2.27\times 10^{-3}{0.0245^2}}\ +\ 1.60}\\\Rightarow a\ =\ 2.91\ m/s^2$

part (b)

Above expression for the acceleration of the block is only depended on the radius of the pulley.

Radius of the larger pulley = $R_2\ =\ 0.05\ m$

Let $a_2$ be the acceleration of the block while connecting to the larger pulley. $\therefore a\ =\ \dfrac{mg}{\dfrac{I}{R_2^2}\ +\ m}\\\Rightarrow a\ =\ \dfrac{1.60\times 9.81}{\dfrac{2.27\times 10^{-3}{0.05^2}\ +\ 1.60}}\\\Rightarow a\ =\ 6.25\ m/s^2$

4 0

3 years ago

A car moving at a speed of 20m/s has a kinetic energy of 300,000 J what’s the cars mass

Alexxx [7]

Answer:

Explanation:

The mass of the car can be found by using the formula

$m = \frac{2k}{ {v}^{2} } \\$

From the question we have

$m = \frac{2 \times 300000}{ {20}^{2} } = \frac{600000}{400} = \frac{6000}{4} \\$

We have the final answer as

Hope this helps you

7 0

3 years ago

How to use Da Vinci flying pedulum clock

schepotkina [342]

Da Vinci was fascinated by how timepieces operate. Based on one of his sketches, it uses the laws of motion and a vertical "flying" pendulum escapement to keep accurate time.
The pendulum's weights, in a bucket suspended from a crane-style arm, act as the clock's power source. The weights propel the pendulum from vertical post to vertical post. As it "flies" it turns precision gears, which in turn keep time. To speed up or slow the clock, adjust the weight-balance of the pendulum by adding or removing weights.

8 0

3 years ago