If the 30 N on the rope were pulled straight up, it would offset the force of gravity ( m g = 10 kg * 9.8 N/kg = 98 N) , leaving a net force up from the ground on the sled of 98-30 = 68 N. Since the rope is pulled at the angle of 25o, only part of the force is in the upward direction, (30N)(sin(25) = (30)(.423) = 12.7. So the net force becomes 98 N down offset by 12.7 up or 98-12.7 = 85.3 N. Ah, there it is: C.
Answer:
Explanation:
b ) The problem is based on Doppler's effect of sound
f = f₀ x (V - v₀) /(
)
f is apparent frequency ,f₀ is real frequency , V is velocity of sound , v₀ is velocity of observer going away ,
is velocity of source going away
778 = 840 x (340 - 14)/ (340 +
)
340 +
= 341.18
= 1.18 m /s
it will go away from the observer or the cyclist.
speed of train = 1.18 m /s
a )
For a stationary observer v₀ = 0
f = f₀ x V /(
)
= 840 x 340 / (340 + 1.180)
= 837 Hz
Answer:
it states that energy can neither be created or destroyed