Answer:
The answer is C. 120,000 J.
Explanation:
Answer:
(C) Only if it starts moving
Explanation:
We know that work done is given by

So there are two case in which work done is zero
First case is that when force and displacement are perpendicular to each other
And other case is that when there is no displacement
So for work to be done there must have displacement, if there is no displacement then there is no work done
So option (c) will be the correct option
Earths atmosphere heats up polars melt
Answer:
11.48 m
Explanation:
A brick starts from rest and gains a speed of 15 m/s and accelerates at 9.8 m/s^2
u = 0
v= 15
a= 9.8
s= ?
V^2 = U^2 + 2as
15^2 = 0^2 + 2 × 9.8×s
225= 19.6s
s= 225/19.6
s = 11.48m
Hence the brick will fall 11.48 m
Answer:
Explanation:
height of pole = 15 ft
height of man = 6 ft
Let the length of shadow is y .
According to the diagram
Let at any time the distance of man is x.
The two triangles are similar

15 y - 15 x = 6 y
9 y = 15 x

Differentiate with respect to time.

As given, dx/dt = 4 ft/s

ft/s