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3 years ago

a basketball player jumped straight up to grab a rebound. If she was in the air for .8 second how high did she jump

1 answer:

5 0

Answer:
0.78m (rounded to nearest hundredth of a meter)

explanation:
time taken for going up=time taken for drop down after reaching the highest point. at the highest point, the velocity becomes 0.

now all thats left is dropping an object from a height (h) and seeing how long it takes to reach the ground. then find out the flight’s total time divided by 2 (0.8/2=0.4)

lets say the velocity is v and the height she jumped to is h. we can make a kinematic expression:
s=vt+½gt²

once we put it all together you should get this:

h=0×0.4+½(9.81) 0.4²

.
∴
Time taken for downward drop
=
0.8
2
=
0.4
s
Suppose that she jumped with initial velocity
=
u

Also suppose that she jumped to a height
h
Using following kinematic expression
s
=
u
t
+
1
2
g
t
2
and inserting various quantities we get
h
=
0
×
0.4
+
1
2
(
9.81
)
0.4
2

h
=
0.78
m
rounded to nearest hundredth of a meter.

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Conductors allow electric charges to move freely

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4 years ago

What units should be used when measuring the mass of a ladybug?

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3 years ago

An open 1-m-diameter tank contains water at a depth of 0.7 m when at rest. As the tank is rotated about its vertical axis the ce

Mamont248 [21]

Answer:

Explanation:

To find the angular velocity of the tank at which the bottom of the tank is exposed

From the information given:

At rest, the initial volume of the tank is:

$V_i = \pi R^2 h_i --- (1)$

where;

height h which is the height for the free surface in a rotating tank is expressed as:

$h = \dfrac{\omega^2 r^2}{2g} + C$

at the bottom surface of the tank;

r = 0, h = 0

∴

$h = \dfrac{\omega^2 r^2}{2g} + C$

0 = 0 + C

C = 0

Thus; the free surface height in a rotating tank is:

$h=\dfrac{\omega^2 r^2}{2g} --- (2)$

Now; the volume of the water when the tank is rotating is:

dV = 2π × r × h × dr

Taking the integral on both sides;

$\int \limits ^{V_f}_{0} \ dV = \int \limits ^R_0 \times 2 \pi \times r \times h \ dr$

replacing the value of h in equation (2); we have:

$V_f} = \int \limits ^R_0 \times 2 \pi \times r \times ( \dfrac{\omega ^2 r^2}{2g} ) \ dr$

$V_f = \dfrac{ \pi \omega ^2}{g} \int \limits ^R_0 \ r^3 \ dr$

$V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{r^4}{4} \Big]^R_0$

$V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{R^4}{4} \Big] --- (3)$

Since the volume of the water when it is at rest and when the angular speed rotates at an angular speed is equal.

Then $V_f = V_i$

Replacing equation (1) and (3)

$\dfrac{\pi \omega^2}{g}( \dfrac{R^4}{4}) = \pi R^2 h_i$

$\omega^2 = \dfrac{4g \times h_i }{R^2}$

$\omega =\sqrt{ \dfrac{4g \times h_i }{R^2}}$

$\omega = \sqrt{\dfrac{4 \times 9.81 \ m/s^2 \times 0.7 \ m}{(0.5)^2} }$

$\omega = \sqrt{109.87 }$

$\mathbf{\omega = 10.48 \ rad/s}$

Finally, the angular velocity of the tank at which the bottom of the tank is exposed = 10.48 rad/s

6 0

3 years ago

A 5000kg car traveling at 40m/s crashes into a wall and comes to a complete stop in 10ms. What was the force on the wall?

Kisachek [45]

Answer:

20,000,000 N

Explanation:

First find the acceleration:

a = Δv / Δt

a = (0 − 40 m/s) / 0.010 s

a = -4000 m/s²

Next use Newton's second law to find the force on the car:

F = ma

F = (5000 kg) (-4000 m/s²)

F = -20,000,000 N

According to Newton's third law, the force on the wall is equal and opposite the force on the car.

F = 20,000,000 N

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3 years ago

By 1949 Americans who lived within the range of a television stations in the country could watch TV, vastly changing the way tha

fredd [130]

Answer: Microwaves.

Explanation: First, we have a trivial answer, and that is the visible light, which is responsible to let the information on the tv to be seen by the user.

Now, TV technology was possible thanks to the microwaves, that are used because these can carry more energy than other types, and these microwaves needed a special technology because they couldn't be handled by the current technology at the time.

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4 years ago