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
kap26 [50]
3 years ago
13

A ball is thrown straight down with a speed of Va2.00 from a building 40.00 meters high. How much S time passes before the ball

reaches the ground? a.) -3.07s b.) - 2.46 s c.) =2.66s d.) =9.89s e.) None of the above.A ball is thrown straight down with a speed of Va2.00 from a building 40.00 meters high. How much S time passes before the ball reaches the ground? a.) -3.07s b.) - 2.46 s c.) =2.66s d.) =9.89s e.) None of the above.
Physics
1 answer:
-Dominant- [34]3 years ago
6 0

Answer:

Option C is the correct answer.

Explanation:

Considering vertical motion of ball:-

Initial velocity, u =  2 m/s

Acceleration , a = 9.81 m/s²

Displacement, s = 40 m

We have equation of motion s= ut + 0.5 at²

Substituting

   s= ut + 0.5 at²

    40 = 2 x t + 0.5 x 9.81 x t²

   4.9t²  + 2t - 40 = 0

   t = 2.66 s   or t = -3.06 s

So, time is 2.66 s.

Option C is the correct answer.

You might be interested in
A tradesman sharpens a knife by pushing it with a constant force against the rim of a grindstone. The 30-cm-diameter stone is sp
Lorico [155]

Answer:

a. 0.21 rad/s2

b. 2.205 N

Explanation:

We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds

200 rpm = 200 * 2π / 60 = 21 rad/s

180 rpm = 180 * 2π / 60 = 18.85 rad/s

r = d/2 = 30cm / 2 = 15 cm = 0.15 m

a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

\alpha = \frac{\Delta \omega}{\Delta t} = \frac{21 - 18.85}{10} = 0.21 rad/s^2

b) Assume the grind stone is a solid disk, its moment of inertia is

I = mR^2/2

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

I = 28*0.15^2/2 = 0.315 kgm^2

So the friction torque is

T_f = I\alpha = 0.315*0.21 = 0.06615 Nm

The friction force is

F_f = T_f/R = 0.06615 / 0.15 = 0.441 N

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

N = F_f/\mu = 0.441/0.2 = 2.205 N

7 0
3 years ago
What information is given by the formula of an ionic compound?
Sergio [31]
MgCl2 is ionic compound.........Mg +2 and Cl -1
both charges are cross multiplied to each element......formula tells us that to balance the positive and negative charges on both sides they are cross multiplied........MgCl2......meaning there is one atom of Mg and 2 atoms of Cl.......

HOPE IT HELPS !!!
4 0
3 years ago
A car with a mass of 725 kg is moving at 32 m/s toward the east. What is the momentum of the car? A second car with a mass of 2,
Elden [556K]

Answer:

A compact car, with mass 725 kg, ... at 115 km/h toward the east. ... b. A second car, with a mass of 2175 kg, has the same momentum. What is its ... Glisens : m = 2175 kg;. D 21,32 xrolka. anknown. r = ? 110.6 mis east

Explanation:

7 0
3 years ago
12. A rocket, initially at rest on the ground, accelerates vertically. It accelerates uniformly until it
vodomira [7]

Answer:

We kindly invite you to read carefully the explanation and check the image attached below.

Explanation:

According to this problem, the rocket is accelerated uniformly due to thrust during 30 seconds and after that is decelerated due to gravity. The velocity as function of initial velocity, acceleration and time is:

v_{f} = v_{o}+a\cdot (t-t_{o}) (1)

Where:

v_{o} - Initial velocity, measured in meters per second.

v_{f} - Final velocity, measured in meters per second.

a - Acceleration, measured in meters per square second.

t_{o} - Initial time, measured in seconds.

t - Final time, measured in seconds.

Now we obtain the kinematic equations for thrust and free fall stages:

Thrust (v_{o} = 0\,\frac{m}{s}, a = 30\,\frac{m}{s^{2}}, t_{o} = 0\,s, 0\,s\le t< 30\,s)

v = 30\cdot t (2)

Free fall (v_{o} = 900\,\frac{m}{s}, a = -9.807\,\frac{m}{s}, t_{o} = 30\,s, 30\,s \le t \le 120\,s)

v = 900-9.81\cdot (t-30) (3)

Now we created the graph speed-time, which can be seen below.

5 0
3 years ago
The local high school is installing new bleachers at the stadium and must also add handrails to meet code. The students know the
Advocard [28]

Answer:

The handrails must be approximately 10.63 meters long

Explanation:

The given parameters are;

The height of the bleachers, h = 8 m

The depth of the bleachers, d = 7 m

The length of the hand rails to go along the bleachers from bottom to top is given by Pythagoras' Theorem as follows;

The length of the hand rail = √(d² + h²)

∴ The length of the hand rail = √(7² + 8²) = √113 ≈ 10.63

In order for the handrails to go along the bleachers from top to bottom, they must be approximately 10.63 meters long.

5 0
3 years ago
Other questions:
  • A rock at rest has weight 138 n. what is the weight of the rock when it is accelerating downward at 3.5 m/s2?
    14·1 answer
  • When the sun heats up the surface of a puddle of water
    10·1 answer
  • What are the three categories of adult development?
    9·1 answer
  • A rocket with mass 5.00 X 103 kg is in a circular orbit of radius 7.20 X 106 m around the earth. The rocket’s engines fire for a
    13·2 answers
  • If the strings have the same thickness butdifferent lengths, which of the following parameters, if any, willbe different in the
    15·1 answer
  • A coil has an inductance of 5 H and a resistance of 20 Ω. If a DC voltage of 100 V is applied to the coil, find the energy store
    10·1 answer
  • A 200 turn coil is in a uniform magnetic field that is decreasing at the rate 0.20 T/s. The coil is perpendicular to the field a
    14·1 answer
  • A train is traveling at 28 m/s. It slows to 6 m/s in 4 s. Calculate the distance the train
    13·2 answers
  • The car was moving at a constant velocity of 5m/s<br> HELP PLS
    15·1 answer
  • Anino acids are important to the body because they build
    7·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!