Retrograde. Planets seem to move forward and then backward sometimes. This is really because we pass them as we move in our orbit but astronomers wanted to try to describe the solar system with earth at the center so elaborate models were employed.
Answer:
A. 40N
B. 5m/s
Explanation:
A.
Impulse is equal to the area under the curve of a force vs. time graph. In this case, the area is in the shape of a triangle with base 8 (12-4=8) and perpendicular height 10:
<em>Area of a triangle = (1/2)bh</em>
A=(1/2)*8*10
=40
ANSWER: 40N
B.
<em>Impulse = mass * velocity</em>
40 = 8v
v = 5
ANSWER: 5m/s
The total mechanical energy of the block-spring system is given by the sum of the potential energy and the kinetic energy of the block:

where
k is the spring constant
x is the elongation/compression of the spring
m is the mass of the block
v is the speed of the block
At the point of maximum displacement of the spring, the velocity of the block is zero: v=0, so the kinetic energy is zero and the mechanical energy is just potential energy of the spring:

(1)
where we used x=A, the amplitude (which is the maximum displacement of the spring).
Since we know
A = 11.0 cm= 0.11 m
E = 1.10 J
We can re-arrange (1) to find the spring constant:
Reflection. It occurs when a wave bounces from the surface of an obstacle
Answer:
a) g.p.e.=mass × gravitational field strength × height
b) Eᵖ= 50 × 9.8 × 20
9800 (J)