Their relative speed is the sum of 60 and 40 or 100km/hr. They will travel the 150km in 1.5 hrs. When two object approach each other, the closing speed is just the sum of the speeds, therefore, the closing speed is your case is 100kph. So they will meet in 1.5 hours.
Answer:
i think its C hope this is rhight have a good day
Explanation:
As the speed is a scalar quantity as it has the only magnitude in it. Therefore, the average speed is also stated as a scalar quantity.
Hence, the correct answer is (B)
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.
Answer:

Explanation:
Given:
Thickness of the paperweight cube, 
apparent depth from one side of the inbuilt paper in the plastic cube, 
apparent depth from the other side of the inbuilt paper in the plastic cube, 
Now as we know that refractive index is given as:

- Let the real depth form first side of the slab be,

- Then the depth from the second side of the slab will be,

Since refractive index for an amorphous solid is an isotropic quantity so it remains same in all the direction for this plastic.




Now the refractive index:


