The gravitational force <em>F</em> between two masses <em>M</em> and <em>m</em> a distance <em>r</em> apart is
<em>F</em> = <em>G M m</em> / <em>r</em> ²
Decrease the distance by a factor of 7 by replacing <em>r</em> with <em>r</em> / 7, and decrease both masses by a factor of 8 by replacing <em>M</em> and <em>m</em> with <em>M</em> / 8 and <em>m</em> / 8, respectively. Then the new force <em>F*</em> is
<em>F*</em> = <em>G </em>(<em>M</em> / 8) (<em>m</em> / 8) / (<em>r</em> / 7)²
<em>F*</em> = (1/64 × <em>G M m</em>) / (1/49 × <em>r</em> ²)
<em>F*</em> = 49/64 × <em>G M m</em> / <em>r</em> ²
In other words, the new force is scaled down by a factor of 49/64 ≈ 0.7656, so the new force has magnitude approx. 76.56 N.
Answer:
Speed of physicist car is 0.036c or 1.08 x 10⁷ m/s .
Explanation:
Doppler Effect is defined as the change in frequency or wavelength of the wave as the source or/and observer moving away or towards each other.
In this case, the Doppler effect equation in terms of wavelength is :
......(1)
Here
is source wavelength,
is observed wavelength, v is speed of the observer and c is the speed of light.
Given :
Source wavelength,
= 660 nm = 660 x 10⁻⁹ m
Observed wavelength,
= 555 nm = 555 x 10⁻⁹ m
Substitute these values in the equation (1).






v = 1.08 x 10⁷ m/s
<em><u>1.car</u></em><em><u> </u></em><em><u>towing</u></em>
<em><u>2.pulling</u></em><em><u> </u></em><em><u>bucket</u></em><em><u> </u></em><em><u>of</u></em><em><u> </u></em><em><u>water</u></em>
<em><u>3.gym</u></em><em><u> </u></em><em><u>equipment</u></em><em><u> </u></em>
<em><u>4.crane</u></em><em><u> </u></em><em><u>machine</u></em>
<em><u>5.tug</u></em><em><u> </u></em><em><u>of</u></em><em><u> </u></em><em><u>war</u></em>
Answer:
cần cung cấp 70 độ vì nước sôi ở 100°C
Explanation: