Answer:
560 m/s
Explanation:
Given,
Frequency ( f ) = 80 hz
Wavelength ( λ ) = 7.0 m = 7m
To find : Velocity ( v )
Formula : -
v = f λ
v = 80 x 7
v = 560 m/s
Hence, the velocity of the wave is 560 m/s.
Answer:
The separation between the charges was decreased by a factor of 0.2
Explanation:
The Coulomb's force between two charges is given by;

r₂ = 0.2r₁
Therefore, the separation between the charges was decreased by a factor of 0.2.
Answer:


Explanation:
A denotes Alex
M denotes Mary
r = Distance from center
Mary and Alex will have the equal displacements in equal interval of time as they are in uniform circular motion. So,

Tangential speed speed is given by

The tangential speed of Mary is 
Answer:
A concave mirror has a radius of curvature of 20 cm. What is it's focal length? If an object is placed 15 cm in front of it, where would the image be formed? What is it's magnification?
The focal length is of 10 cm, object distance is 30 cm and magnification is -2.
Explanation:
Given:
A concave mirror:
Radius of curvature of the mirror, as C = 20 cm
Object distance in-front of the mirror = 15 cm
a.
Focal length:
Focal length is half of the radius of curvature.
Focal length of the mirror =
= 10 cm
According to the sign convention we will put the mirror on (0,0) point, of the Cartesian coordinate open towards the negative x-axis.
Object and the focal length are also on the negative x-axis where focal length and image distance will be negative numerically.
b.
We have to find the object distance:
Formula to be use:
⇒ 
⇒ Plugging the values.
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
Image will be formed towards negative x-axis 30 cm away from the pole.
c.
Magnification (m) is the negative ratio of mage distance and object distance:
⇒ 
⇒ 
⇒ 
The focal length of the concave mirror, is of 10 cm, object distance is 30 cm and magnification is -2.