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4 years ago

10

A ball is thrown downward from the top of a 55.0 m tower with an initial speed of 15.0 m/s. Assuming negligible air resistance,

what is the speed of the ball just before hitting the ground?

1 answer:

vitfil [10]4 years ago

3 0

Answer:

36.4m/s

Explanation:

According to equation of motion,

v² = u²+2as where;

v is the final velocity

u is the initial velocity = 15m/s

a is the acceleration due to gravity = +g (it is positive because the body is thrown downwards.)

g = 10m/s²

s will be the distance from the top of the tower from which it is thrown

S = 55.0m

Substituting this value to get the final velocity, we have;

v² = 15²+2(10)(55)

v² = 225+1100

v² = 1325

v =√1325

v = 36.4m/s

Therefore, the speed of the ball just before hitting the ground will be 36.4m/s

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A ball is thrown horizontally from the top of a building 54 m high. The ball strikes the ground at a point 35 m horizontally awa

Ivanshal [37]

Answer:

V=34.2 m/s

Explanation:

Given that

Height , h= 54 m

Horizontal distance , x = 35 m

Given that , the ball is thrown horizontally , therefore the initial vertical velocity will be zero.

In vertical direction :

We know that

$V^2_y=U^2_y+2 g h$

Now by putting the values in the above equation we got

$V^2_y=U^2_y+2 g h$

$V^2_y=0^2+2\times 9.81 \times 54$

Assume $g= 9.81 m/s^2$

Thus

$V^2_y=1059.48$

$V_y=\sqrt{1059.48}\ m/s$

$V_y=32.54 m/s$

We also know that

$V_y=U_y+ g\times t$

$32.54=9.81\times t$

$t=\dfrac{32.54}{9.81}=3.31\ s$

In horizontal direction :

$x=U_x\times t$

$U_x=\dfrac{35}{3.31}=10.54\ m/s$

Thus the resultant velocity

$V=\sqrt{V^2_y+U^2_x}$

$V=\sqrt{32.54^2+10.54^2}=34.2\ m/s$

V=34.2 m/s

Therefore the velocity will be 34.2 m/s.

5 0

4 years ago

How do i do this question？just number 5

larisa86 [58]

5 a)

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$4000 \; \text{m} \cdot \text{s}^{-1}$ - Wood (solid)

$1500 \; \text{m} \cdot \text{s}^{-1}$ - Sea Water (liquid)
$1200 \; \text{m} \cdot \text{s}^{-1}$ - Acetone (liquid)
$1100 \; \text{m} \cdot \text{s}^{-1}$ - Alcohol (liquid)

$972 \; \text{m} \cdot \text{s}^{-1}$ - Helium (gas)
$267 \; \text{m} \cdot \text{s}^{-1}$ - Carbon dioxide (gas)

What trend do you identify from these data? Here's what I've got:

$\text{Sonic Speed}: \text{solid} > \text{liquid} > \text{gas}$

5 b)

The way microscopic particles are arranged in a substance helps distinguish between different physical states:

Particles in a solid are held tightly in place with small separation in between; it's hard for particles in a solid to move past one another; solids therefore have shapes that persists over time.
Particles in a gas are highly mobile- they keep moving AT ALL TIMES. There are large separations between individual particles and therefore gases tend to show no definite shape or volume.
The arrangement of particles in a liquid is located somewhere in between that of solids and gases. The exact configuration is dependent on the nature of the liquid- for example, molecules in maple syrup are held way closer to each other than those in distilled water are.

Sound travels as a longitudinal wave. As a sound wave passes through a medium, individual particles become excited and gain energy; as they run into others they transfer their energy to the next particle; the sound wave thus propagate across the medium. With a lower average distance between individual particles this action can proceed at a greater rate in average solids than in average liquids, and in average liquids than in average gases. Hence the trend.

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