Average speed =
(total distance)/(total time)
Average speed = (99+90)/(2+3)
That's (189 km) / (5 hr)
Average speed = 37.8 km/hr
A mass weighing 32 pounds stretches a spring 2 feet.
(a) Determine the amplitude and period of motion if the mass is initially released from a point 1 foot above the equilibrium position with an upward velocity of 6 ft/s.
(b) How many complete cycles will the mass have completed at the end of 4 seconds?
Answer:
Period = 
seconds
8 cycles
Explanation:
A mass weighing 32 pounds stretches a spring 2 feet;
it implies that the mass (m) = 
m= 
= 1 slug
Also from Hooke's Law
2 k = 32
k = 
k = 16 lb/ft
Using the function:
(because of the initial position being above the equilibrium position)
( as a result of upward velocity)
NOW, we have:
However;
means
also implies that:
Hence, 
Period can be calculated as follows:
= 
= seconds
How many complete cycles will the mass have completed at the end of 4 seconds?
At the end of 4 seconds, we have:
cycles
Answer:
option (E) is correct.
Explanation:
Work done is defined as the product of force and the distance in the direction of force.
force, f = 100 N
Coefficient of friction, = 0.25
distance = 15 m
So, net force F = f - friction force
F = 100 - 0.25 x m g
Work = (100 - 0.25 mg) x d cosθ
For minimum work, the angle should be maximum.
So, the value of θ is 76°.
thus, option (E) is correct.
Thick lens will have shorter and consequently thin lens will have greater focal length. Because, For a thick lens, the optical path length of the light is more, than for a thin lens, thus, the bending of light will be more in case of a thicker lens. Consequently, it has a shorter focal length.
