Answer:
O B. when the angle between the force and displacement is 90°
Explanation:
<h3>work defined as

. </h3><h3>work can only be done if object moves(displacement) in the direction of force. now a quick one. if you since the varrious angles into the cosine, you would see that Cos 90 will give zero which implies that no work is done. Again, angle means it is perpendicular and so it is not in the direction of force.</h3>
Explanation:
Given that,
Initial speed of the rock, u = 30 m/s
The acceleration due to gravity at the surface of the moon is 1.62 m/s².
We need to find the time when the rock is ascending at a height of 180 m.
The rock is projected from the surface of the moon. The equation of motion in this case is given by :

It is a quadratic equation, after solving whose solution is given by:
t = 7.53 s
or
t = 8 seconds
(e)If it is decending, v = -20 m/s
Now t' is the time of descending. So,

Let h' is the height of the rock at this time. So,

or
h' = 155 m
Answer:3.6
Explanation:
Given
Architect decide to double the width
length increases by 50 percent
height increases by 20 percent
Let L,B,H be length,height and width of rectangular room
L'=1.5L
B'=2B
H'=1.2H
therefore new volume V'=L'\times B'\times H'

V'=3.6LBH
new volume is 3.6 times the original
Deposition:
- when a gas changes directly to a solid
- latent heat is released
- physical change, NOT a chemical change
Answer:
A- Martin brings his friends home to meet grandpa.
Explanation:
took the test.