Answer:
last option is the correct one
Answer:
Angle: 
Explanation:
<u>Two-Dimension Motion</u>
When the object is moving in one plane, the velocity, acceleration, and displacement are vectors. Apart from the magnitudes, we also need to find the direction, often expressed as an angle respect to some reference.
Our boy can swim at 3 m/s from west to east in still water and the river he's attempting to cross interacts with him at 2 m/s southwards. The boy will move east and south and will reach the other shore at a certain distance to the south from where he started. It happens because there is a vertical component of his velocity that is not compensated.
To compensate for the vertical component of the boy's speed, he only has to swim at a certain angle east of the north (respect to the shoreline). The goal is to make the boy's y component of his velocity equal to the velocity of the river. The vertical component of the boy's velocity is

where
is the speed of the boy in still water and
is the angle respect to the shoreline. If the river flows at speed
, we now set



I think it is C. I hope I helped.
Answer:
14
Explanation:
A sound wave in a steel rail has a frequency of 620 Hz and a wavelength of 10.5 m. What is the speed of sound in steel? U f = ? S f = 3 x 108 m/s) / 0.06 m 14 so it will be 14
Answer:
Explanation:
We shall apply conservation of mechanical energy
kinetic energy of alpha particle is converted into electric potential energy.
1/2 mv² = k q₁q₂/d , d is closest distance
d = 2kq₁q₂ / mv²
= 2 x 9 x 10⁹ x 79e x 2e / 4mv²
= 1422 x2x (1.6 x 10⁻¹⁹)² x 10⁹ /4x 1.67 x 10⁻²⁷ x (1.5 x 10⁷)²
= 3640.32 x 10⁻²⁹ /2x 3.7575 x 10⁻¹³
= 484.4 x 10⁻¹⁶
=48.4 x 10⁻¹⁵ m