All categories

2 years ago

A soccer player kicks a ball with a speed of 30 m/s at an angle of 10. How long does the ball stay in the air?

1 answer:

4 0

"10" is not a very satisfying description of an angle.
I'll assume it's 10 degrees, and that it's the angle of the initial trajectory
above the horizontal.

The vertical component of the ball's speed is 30 sin(10°) = 5.209 meters per second.

The acceleration of gravity is 9.8 meters per second² downward.

The ball continues to rise for 9.8/5.209 = 1.881 seconds after the kick.
At that time, it reaches the peak of its arc, and if nobody else has contacted it yet,
it begins to fall, and takes the same length of time to return to the ground whence
it was kicked.

So the time between the kick and return to the ground is (2 x 1.881) = <u>3.763 seconds</u>.

Note: As is customary and necessary at the high school level,
we assume no air resistance.

You might be interested in

A 210 Ohm resistor uses 9.28 W of

IgorLugansk [536]

Resistance=R=210Ohm
Power=9.28W=P

Current=I

$\boxed{\sf P=I^2R}$

$\\ \sf\longmapsto I^2=\dfrac{P}{R}$

$\\ \sf\longmapsto I^2=\dfrac{9.28}{210}$

$\\ \sf\longmapsto I^2\approx0.04$

$\\ \sf\longmapsto I\approx\sqrt{0.04}$

$\\ \sf\longmapsto I\approx\sqrt{\dfrac{4}{100}}$

$\\ \sf\longmapsto I\approx\dfrac{\sqrt{4}}{\sqrt{100}}$

$\\ \sf\longmapsto I\approx\dfrac{2}{10}$

$\\ \sf\longmapsto I\approx0.2A$

4 0

2 years ago

Question 8 (1 point) How many protons are in an element with an atomic number of 8 and a mass number of 18? a 3 b 8 c 10 d 18

yarga [219]

Answer: B - 8

Explanation: 8 protons because number of protons is equal to number of atoms in the nucleus.

6 0

3 years ago

You are riding a bicycle. If you apply a forward force of 125 N, and you and

erica [24]

Answer:

1.52g

Explanation:

Given parameters:

Force = 125N

Mass combined = 82kg

Unknown:

Acceleration of the bicycle = ?

Solution:

From Newton second law of motion suggests that:

Force = mass x acceleration

Acceleration = $\frac{force}{mass}$ = $\frac{125}{82}$ = 1.52g

8 0

3 years ago

A 20-lb force acts to the west while an 80-lb force acts 45° east of north. The magnitu 80 lb 70 lb 067 lb 100 lb

natulia [17]

Answer:

option C

Explanation:

given,

force act on west = 20 lb

force act at 45° east of north = 80 lb

magnitude of force = ?

∑ F y = 80 cos 45⁰

F y = 56.57 lb

magnitude of forces in x- direction

∑ F x = -20 + 80 sin 45⁰

= 36.57 lb

net force

F = $\sqrt{F_x^2+F_y^2}$

F = $\sqrt{56.57^2+36.57^2}$

F = 67.36 lb≅ 67 lb

hence, the correct answer is option C

4 0

2 years ago

A turntable with a moment of inertia of 7.2 × − ⋅ rotates freely with an angular speed of 6.5 ⁄ . Riding on the rim of the turnt

irina1246 [14]

Answer:

turntable with a moment of inertia of 7.2 × − ⋅ rotates freely with an angular speed of 6.5 ⁄ . Riding on the rim of the turntable, 2 from the center, is a hamster. When the hamster walks to the center of the turntable, the angular speed of the turntable becomes ⁄. What is the mass of hamster?

Explanation:

6 0

2 years ago