Friction always acts opposite to the motion.<em> (B)</em>
Answer:
Force is 432.94 N along the rebound direction of ball.
Explanation:
Force is rate of change of momentum.

Final momentum = 0.38 x -1.70 = -0.646 kgm/s
Initial momentum = 0.38 x 2.20 = 0.836 kgm/s
Change in momentum = -0.646 - 0.836 = -1.472 kgm/s
Time = 3.40 x 10⁻³ s

Force is 432.94 N along the rebound direction of ball.
The incorrect statement about electromagnetic waves is C. induction of electric fields by changing magnetic fields only occurs if a conducting material is present.
Electromagnetic waves do not rely on any medium for propagation, which means that the generation of fields is irrespective of the presence of a conducting material.
Answer:
The maximum height the box will reach is 1.72 m
Explanation:
F = k·x
Where
F = Force of the spring
k = The spring constant = 300 N/m
x = Spring compression or stretch = 0.15 m
Therefore the force, F of the spring = 300 N/m×0.15 m = 45 N
Mass of box = 0.2 kg
Work, W, done by the spring =
and the kinetic energy gained by the box is given by KE = 
Since work done by the spring = kinetic energy gained by the box we have
=
therefore we have v =
=
=
= 5.81 m/s
Therefore the maximum height is given by
v² = 2·g·h or h =
=
= 1.72 m
We use the equation of motion for vertical component,

Here,
is displacement of bullet,
is vertical initial velocity of bullet which is equal to zero because bullet was fired horizontally, and t is time of flight.
Therefore,

Given, 
Substituting the values, we get time of flight
