1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
OLga [1]
3 years ago
10

A player kicks a football (from the ground) at an initial angle of 30°. The football is in the air for 2.4 s before it hits an o

pposing player. The opposing player was a horizontal distance x = 50 m away from where the football was kicked. What was the initial horizontal velocity component of the football?

Physics
1 answer:
wolverine [178]3 years ago
8 0

Answer:

The initial horizontal velocity was 21 m/s

Explanation:

Please, see the figure for a better understanding of the problem.

The equation for the position of an object moving in a parabolic trajectory is as follows:

r = (x0 + v0 · t · cos α, y0 + v0 · t · sin α + 1/2 · g ·t²)

Where:

r = vector position at time t

x0 = initial horizontal position

v0 = initial velocity

t = time

α = launching angle

y0 = initial vertical position

g = acceleration due to gravity

Notice that at time t = 2.4 s the vector "r" is the one in the figure. We know that the x-component of that vector is 50 m. Then using the equation for the x-component of the vector "r", we can calculate the initial velocity:

x = x0 + v0 · t · cos α

Let´s place the center of the frame of reference at the point of the kick so that x0 = 0.

x =  v0 · t · cos α

x/t = v0 · cos α

Notice in the figure that v0 · cos 30° = v0x which is the initial horizontal velocity. Remember trigonometry of right triangles:

cos α = adjacent / hypotenuse = v0x / v0

Then:

50 m/ 2.4 s = v0 · cos 30° = v0x

v0x = 21 m/s

You might be interested in
An object is accelerating if it is moving____. circle all that apply. ​
tino4ka555 [31]

Answer:

With changing speed and/or in a circle

3 0
3 years ago
A person drives a car around a circular road with a constant speed of 20 m/s. The
ale4655 [162]

Answer:

16 m/s^2

Explanation:

acceleration tangential = (v^2)/r

a=400/25

a=16 m/s^2

Side note: next time, be more specific when asking about acceleration in circular motion. There's more than one type! Example:

angular acceleration=acceleration tangential/r

angular acc.=16/25

angular acc.=0.64 rad/s^2

5 0
3 years ago
Read 2 more answers
NASA developed a reflective foil barrier to help shield spacecraft from heat transfer in space. These reflective barriers are no
morpeh [17]

Answer: Radiation

Explanation: Radiation is the energy that comes from a source in form of electromagnetic waves, subatomic particles, light, or heat which travels through space.

Examples of radiation include the light, heat, and particles emitted from the Sun.

Using a foil barrier to prevent heat transfer is possible because foil has a silver color, and silver reflects light and heat instead of absorbing them. This is the opposite of black surfaces that absorb heat.

So in homes where these foil reflective barriers are used, the transfer of heat through Radiation is highly reduced.

3 0
3 years ago
How much power is needed to lift the 200-N object to a height of 4 m in 4 s?
Vitek1552 [10]

Answer: 2000 watts

Explanation:

Given that,

power = ?

Weight of object = 200-N

height = 4 m

Time = 4 s

Power is the rate of work done per unit time i.e Power is simply obtained by dividing work by time. Its unit is watts.

i.e Power = work / time

(since work = force x distance, and weight is the force acting on the object due to gravity)

Then, Power = (weight x distance) / time

Power = (200N x 4m) / 4s

Power = 8000Nm / 4s

Power = 2000 watts

Thus, 2000 watts of power is needed to lift the object.

3 0
3 years ago
If gravity on the earth increased, what affect would it have on the moon
Rufina [12.5K]

Answer:

If gravity on Earth is increased, this gravitational tugging would have influenced the moon's rotation rate. If it was spinning more than once per orbit, Earth would pull at a slight angle against the moon's direction of rotation, slowing its spin. If the moon was spinning less than once per orbit, Earth would have pulled the other way, speeding its rotation.

6 0
3 years ago
Other questions:
  • you are sitting in a cart at the top of a hill on a roller coaster. you have 10,500 j of gravitational potential energy. if your
    7·1 answer
  • There are eight men sitting on a couch. Three legs break and six men leave. How many legs are remaining
    15·2 answers
  • Use the position equation given below, where s represents the height of the object (in feet), v0 represents the initial velocity
    15·1 answer
  • A 140 g ball at the end of a string is revolving uniformly in a horizontal circle of radius 0.537 m. The ball makes 2.27 revolut
    5·1 answer
  • Energy conversion for a man stepping off a cliff
    10·1 answer
  • The unit for measuring heat is:<br> 1.Kelvin<br> 2.Watts<br> 3.Newtons<br> 4.Joules
    10·2 answers
  • PLEASE ANSWER THIS WORKSHEET ITS DUE TODAY WILL GIVE BRAINLIEST BALANCED AND UNBALANCED WORKSHEET
    11·1 answer
  • The single invention of the ______ has advanced what we know about the universe more than any other scientific technology. a. Su
    9·1 answer
  • All of the following are possible transition points that occur during adulthood except __________.
    10·2 answers
  • Two rocks, a and b, are thrown horizontally from the top of a cliff. rock a has an initial speed of 10 meters per second and roc
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!