When a plane minor is placed horizontally on level ground at a distance of om from the foot of tower the top of the tower and its image in the mirror subtend an angle of 90" at the eye. The height of the tower
a) 30m
b) 60m
c) 90 m
d) 120m

b : 60m

Explanation:

when a plane mirror is placed horizontally on a level ground at a distance of 60m from the top of tower as shown in figure. a/c to question, The top of tower and its image in the mirror subtend an angle of 90° at the eyes. so, angle made by top of tower and horizontal line is 45° as

given data:

determine the horse power (h.p) = ?

force applied to move the box(f) = 10 pounds,

box lifted from a distance         (d) = 3 feet

time taken to lift                         (t) = 10 sec,

the horse power is defined as amount of work required to move a load. the horse power is equal to 550 foot-pound per second

                  1 h.p   = 550 foot-pound/second

it can also be defined as the the load that need to be move a body for certain distance in a certain amount of time.

mathematically,

                      h.p = (force × distance)/ time

                            = (10 × 3)/ 10

                            = 30/10

                            = 3 foot -pound/sec

hence, the horse power is needed to move the box is 3 foot-pound/second

important note: 1 h.p = 550 foot-pound/second = 746 watts

c. rb

explanation:

the atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons.