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2 years ago

No links plz!!

Physics

1 answer:

Pavlova-9 [17]2 years ago

6 0

Answer:

Light

Explanation:

The way a concave mirror works is that since it's concave, the light bounces off of each other. a convex mirror, it curved the opposite, and the mirror has no way to bounce off of itself.

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If 27 J of work are needed to stretch a spring from 15 cm to 21 cm and 45 J are needed to stretch it from 21 cm to 27 cm, what i

kupik [55]

Answer:

9 cm.

Explanation:

The energy used for stretch the spring from $15 cm$ to $21 cm$ will be , $E_{1}=27J$

The energy used for stretch the spring from $21 cm$ to $27 cm$ will be , $E_{2}=45J$

using the energy of spring formula ,we find that

$27 = \frac{1}{2}K((21-L^{2})-(15-L^{2}))$

$45 = \frac{1}{2}K((27-L^{2})-(21-L^{2}))$

Dividing both the equation will get,

$\frac{3}{5}=\frac{(21-L)^{2}-(15-L)^{2}}{(27-L)^{2}-(21-L)^{2}}\\5((21-L)^{2}-(15-L)^{2})=3((27-L)^{2}-(21-L)^{2})\\3(729 - 54L + L^{2}- 441 + 42L - L^{2} ) = 5(441 - 42L + L^{2} - 225 + 30L - L^{2} )\\3(288 - 12L) = 5(216 - 12L)\\24L = 216\\L = 9 cm$

Therefore, the natural length of the spring is, 9 cm.

4 0

3 years ago

Darren drives to school in rush hour traffic and averages 28 mph. He returns home in mid-afternoon when there is less traffic an

Gala2k [10]

Answer:

distance between school and home is 21 miles

Explanation:

given data

in rush hour speed s1 = 28 mph

less traffic speed s2 = 42 mph

time t = 1 hr 15 min = 1.25 hr

to find out

distance d

solution

we consider here distance home to school is d and t1 time to reach at school

we get here distance equation when we go home to school that is

distance = 28 × t1 .......................1

and when we go school to home distance will be

distance = 42 × ( t - t1 )

distance = 42 × ( 1.25 - t1 ) ...................2

so from equation 1 and 2

28 × t1 = 42 × ( 1.25 - t1 )

t1 = 0.75

from equation 1

distance = 28 × t1

distance = 28 × 0.75

distance = 21 miles

4 0

3 years ago

Bryan Allen pedaled a human-powered aircraft across the English channel from the cliffs of Dover to Cap Gris-Nez on June 12, 197

tigry1 [53]

Answer:

The answer is " $5.53 \ \frac{m}{s}$ "

Explanation:

apply the formula for calculating the average velocity to the relative air

$V_{PG} =V_{PA}+V_{AG}$

$\Rightarrow V_{PA} = V_{PG} -V_{AG}$

Given value:

$V_{AG} = -2 \ \frac{m}{s}$

$V_{PG} =3.53$

$\Rightarrow V_{PA} = 3.53 - (-2) \\\\\Rightarrow V_{PA} = 3.53 +2 \\\\\Rightarrow V_{PA} = 5.53 \\\\$

The final answer is " $5.53 \ \frac{m}{s}$ " in the south-east direction.

4 0

3 years ago

A car is traveling at 7.0 m/s when the driver applies the brakes. The car moves 1.5 m before it comes to a complete stop. If the

viva [34]

Answer:

d. 6.0 m

Explanation:

Given;

initial velocity of the car, u = 7.0 m/s

distance traveled by the car, d = 1.5 m

Assuming the car to be decelerating at a constant rate when the brakes were applied;

v² = u² + 2(-a)s

v² = u² - 2as

where;

v is the final velocity of the car when it stops

0 = u² - 2as

2as = u²

a = u² / 2s

a = (7)² / (2 x 1.5)

a = 16.333 m/s

When the velocity is 14 m/s

v² = u² - 2as

0 = u² - 2as

2as = u²

s = u² / 2a

s = (14)² / (2 x 16.333)

s = 6.0 m

Therefore, If the car had been moving at 14 m/s, it would have traveled 6.0 m before stopping.

The correct option is d

4 0

3 years ago

A crowbar makes our work easier by multiplying effort true or false

OLEGan [10]

Answer:

True

Explanation:

A crowbar makes our work easier by multiply effort because it belongs to first class lever.

And first class lever makes work easier by multiplying the effort

6 0

3 years ago