A ) The displacement:
d = v o t - (gt²) / 2 =
= 19.6 m/s × 1 s - ( 9.8 m/s² x 1 s² ) / 2 =
= 19.6 m - 4.9 m = 14.7 m
b ) v = v o - g t
0 = 19.6 m/s - 9.8 t ( when the ball is at the highest point )
9.8 t = 19.6
t = 19.6 : 9.8
t = 2 s
h = v o t - (gt²)/2 = 19.6 x 2 - ( 9.8 x 4 ) / 2 = 39.2 - 19.6
h = 19.6 m
c ) h = gt² / 2
19.6 = 9.8 t²/2
9.8 t² = 39.2
t² = 39.2 : 9.8
t² = 4
t 2 = 2 s ( and we know that t 1 = 2 s )
t = t 1 + t 2 = 2 s + 2 s = 4 s
Answer:
Explanation:
Given
Force=18lb
extension=8in
Using Hooke's law to get the spring constant(k)
F=ke
Then,
K=f/e
K=18/8
K=2.25lb/in
Work done by spring is given by
W=1/2Fe
Or W=1/2ke²
Then,
Work done in stretching the spring to 14in
W=1/2ke²
W=0.5×2.25×14²
W=220.5lbin
1 Inch-pounds Force to Joules = 0.113J
Then, to joules
W=0.133×220.5
W=29.33J
The amount or cost that the user of the energy-efficient bulb save during 100h of use will be $0.319.
<h3>How to calculate the cost?</h3>
For the 11.0W bulb, it should be noted that the value will be:
= 11.0 × 100 × (1/1000) × 0.110
= $0.121
The 40W bulb will be:
= 40 × 100 × (1/1000) × 0.110
= $0.44
Therefore, the amount that will be saved will be:
= $0.44 - $0.121
= $0.319
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