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Rudik [331]
3 years ago
8

A ball whose mass is 0.3 kg hits the floor with a speed of 7 m/s and rebounds upward with a speed of 4 m/s. if the ball was in c

ontact with the floor for 1.5 ms (1.5multiply10-3 s), what was the average magnitude of the force exerted on the ball by the floor? favg = 602.94 incorrect: your answer is incorrect. n.
Physics
1 answer:
Maurinko [17]3 years ago
8 0
Newton's second law is stated as:
F=ma,

a = (7-4)/1.5 = 2 m/s^2 (it is a deceleration due to impact with floor. And thus the ball exerts force on the floor).

Therefore,

F= 0.3*2 = 0.6 N
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A sun-like star is barely visible to naked-eye observers on earth when it is a distance of 7.0 light years, or 6.6 * 1016 m, awa
igomit [66]

Answer:

At a distance of 1376.49 candle emits 0.2 watt power

Explanation:

Distance between Sun and earth 6.6\times 10^{16}m

Sun emits a power of P=3.8\times 10^{26}watt

Power emitted by candle = 0.20 watt

We know that brightness is given by

B=\frac{P}{4\pi d^2}

So \frac{3.8\times 10^{26}}{4\pi (6\times 10^{16})^2}=\frac{0.20}{4\pi d^2}

3.8\times 10^{26}d^2=7.2\times 10^{32}

d^2=1.89\times 10^6

d=1376.49m

So at a distance of 1376.49 candle emits 0.2 watt power

3 0
3 years ago
An observer in frame S sees lightning simultaneously strike two points 100 m apart. The first strike occurs at xx1 = yy1 = zz1 =
Veseljchak [2.6K]

Answer:

a) 0, = -0.33 us

b) 140m

c) No, The event are not simultaneous i.e they did not occur at the same time, the second even (-0.33 usec) occurs 0.33 usec earlier than the first event.

Explanation:

a)

the lorentz factor expression is written as;

y = 1₀ / √(1 - (v²/c²))

where v  is the relative speed of an observer and c is the speed of light

so we were given that relative speed to be o.7c

therefore

y = 1 / √(1 - ((0.7c)² / c²))

y = 1 / √(1 - (0.49c² / c²))

y = 1 / √(1 - 0.49)

y = 1 / 0.7141

y = 1.4

1 - the coordinates  of the first event, the s' frame of reference is,

x1 ' = y(x1 - vt1) = 0

y1 ' = y1, z1' = z1 and

t1 ' = y [t1 - v/c²x1]

= 0

2 - the coordinates of the second event, the s ' frame of reference is'

x2 ' = y(x2-vt2)

= 1.4(100m - 0)

= 140m

y2 ' = y2, z2 ' = z2

t2 ' = y [ t2 - v/c²x2 ]

= 1.4 [ 0 - 0.7c/c²(100) ]

using speed of light c as 3*10^8

1.4 [ 0 - (0.7*3*10^8) / (3*10^8)²(100) ]

= -0.33 us

b)

distance between

delltaX' = X2' - X1'

= 140m - 0

= 140m

c)

No, The event are not simultaneous i.e they did not occur at the same time.

the second even (-0.33 us) occurs 0.33 us earlier than the first event.

4 0
3 years ago
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W = Fd = 4(2100) = 8400 J

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I was just rewriting my notes on the work lesson I did in class today, so I saw this question at the perfect time!! :)

Hope it helps!! :)
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