Answer:
B,C
Explanation:
In the law of magnetism, like poles repel and unlike poles attract. The north and South Pole attracts which makes B correct. The north and north or south and south poles repel.
In a compass ,the north end of a magnet is attracted to the south magnetic pole which is in close proximity to the geographic South Pole. This makes
Option c correct.
Answer:
Explanation:
Impulse of a force is measured by force x time or F X t
Impulse also equals change in momentum or
F x t = m v₂ - m v₁
The given case is as follows
in the first case
F x t = mv - o = mv
F = mv / t
in the second case
F₁ x 4 t = mv
F₁ = 1/4 x mv /t
F₁ = F / 4
option a) is correct .
iii )
In the last case
F₂ X t = m v/2 -0
F₂ = 1/2 x mv / t
= 1/2 x F
F₂ = F/2
Option e ) is correct.
Answer: The accurate statement which describes the transmission of sound through various medium is D.
Explanation:
Sound is longitudinal wave in which the vibration of particles travels parallel to the propagation of the motion of the wave. It requires a medium to travel. It consists of compression and rarefaction.
Sound insulator prevents the sound to travel for example plastic, wood etc. Sound travels faster in solid medium than in liquid medium. Sound travels faster in liquid than in gas. Less elastic material absorbs sound for example paper in compare to inelastic material.
Therefore, the accurate statement which describes the transmission of sound through various medium is "Sound insulators prevent sound from being transmitted better than elastic solids.
The maximum allowable torque must correspond to the allowable shear stress for maximization. To solve this, we use the torsion formula:
Max. Allowable Shear Stress = Maximum Torque ÷ Cross-Sectional Area
8 x 10^6 Pa = Maximum Torque ÷ pi*(d/2)²
Maximum Torque = 8 x 10^6 Pa * pi*(0.06/2)² m²
Maximum Torque = 22,619.47 J or
Maximum Torque = 22.62 kJ
As for the second question, I have no reference figure so I am unable to answer it. I hope I was still able to help you, though.
90 km/h : 3.6 = 25 m/s. If you know that on earth g = 9.81 m/s^2, then all you have to do is divide the speed by g. 25/9.81 = 2.548 seconds
At least, if by 'gently rolls off a vertical cliff' means that your starting velocity equals zero.
