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Anastasy [175]
3 years ago
13

Suppose a soccer ball is kicked from the ground at an angle 20.0º above the horizontal at 8.00 m/s. The y-velocity is determined

to be 2.74 m/s. How long will the ball be in the air? Assume the ball lands at the same height at which it was kicked.
Physics
1 answer:
julia-pushkina [17]3 years ago
8 0

initial speed of the ball by which it is kicked is 8 m/s

now the angle at which it is kicked is 20 degree

here we will have

v_y = v sin20

v_y = 8 sin20 = 2.74 m/s

now we will have

\Delta y = v_y t + \frac{1}{2}at^2

so if the ball again land on the ground at same level then we have

\Delta y = 0

0 = 2.74 t - \frac{1}{2}(9.8) t^2

0 = 2.74 - 4.9 t

t = 0.56 s

so total time will be 0.56 s

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What is the difference between the B-field and the H-field?
Simora [160]
The H field is in units of amps/meter.  It is sometimes called the auxiliary field. It describes the strength (or intensity) of a magnetic field. The B field is the magnetic flux density.  It tells us how dense the field is.  If you think about a magnetic field as a collection of magnetic field lines, the B field tells us how closely they are spaced together. These lines (flux linkages) are measured in a unit called a Weber (Wb).  This is the analog to the electric charge, the Coulomb.  Just like electric flux density (the D field, given by D=εE) is Coulombs/m²,  The B field is given by Wb/m², or Tesla.  The B field is defined to be μH, in a similar way the D field is defined.  Thus B is material dependent.  If you expose a piece of iron (large μ) to an H field, the magnetic moments (atoms) inside will align in the field and amplify it.  This is why we use iron cores in electromagnets and transformers.
So if you need to measure how much flux goes through a loop, you need the flux density times the area of the loop Φ=BA.  The units work out like 
Φ=[Wb/m²][m²]=[Wb], which is really just the amount of flux.  The H field alone can't tell you this because without μ, we don't know the "number of field" lines that were caused in the material (even in vacuum) by that H field.  And the flux cares about the number of lines, not the field intensity.
I'm way into magnetic fields, my PhD research is in this area so I could go on forever.   I have included a picture that also shows M, the magnetization of a material along with H and B.  M is like the polarization vector, P, of dielectric materials. If you need more info let me know but I'll leave you alone for now!

3 0
3 years ago
The stopwatch used by a student to measure velocity of a pulse in a slinky was of least count 0.1 second. He stops the stopwatch
sweet-ann [11.9K]

Least count of the pulse stopwatch is given by

\Delta t = 0.1 s

this means each division of the stopwatch will measure 0.1 s of time

After 3 journeys from one end to other we can see that total time that is measured here is shown by the clock as 52nd division

So here total time is given as

Time = (Number of division) (Least count)

now we will have

T = 52 \times 0.1s

T = 5.2 s

4 0
3 years ago
A ball starts at rest and rolls down an inclined plane. The ball reaches 7.5 m/s in 3 seconds. What is the acceleration?
just olya [345]

Answer:

a=2.5\ m/s^2

Explanation:

<u>Motion With Constant Acceleration </u>

It's a type of motion in which the velocity of an object changes uniformly over time.

The equation that describes the change of velocities is:

v_f=v_o+at

Where:

a   = acceleration

vo = initial speed

vf  = final speed

t    = time

Solving the equation for a:

\displaystyle a=\frac{v_f-v_o}{t}

The ball starts at rest (vo=0) and rolls down an inclined plane that makes it reach a speed of vf=7.5 m/s in t=3 seconds.

The acceleration is:

\displaystyle a=\frac{7.5-0}{3}

\boxed{a=2.5\ m/s^2}

7 0
3 years ago
Which of the following is a nonferromagnetic material? (a) aluminum (b) iron (c) cobalt (d) gadolinium
ivolga24 [154]

Answer:

A

Explanation:

Iron and gadlinium are both very easily made into magnetic substances.  Cobalt is also capable of being magnetized. Aluminum, put in an alloy, can make a magnetic substance, but

Aluminum by itself is not able to be magnetized.

5 0
3 years ago
A team exerts a force of 10 N towards the south in a tug of war. The other, opposite team, exerts a force of 17 N towards the no
ikadub [295]

Answer:

Option C

Explanation:

According to the question:

Force exerted by the team towards south, F = 10 N

Force exerted by the opposite team towards North, F' = 17 N

Net Force, \vec{F_{net}} = \vec{F'} - \vec{F}

\vec{F_{net}} = \vec{F'} - \vec{F} = 17 - 10 = 7 N

Thus the force will be along the direction of force whose magnitude is higher

Therefore,

\vec{F_{net}} = 7 N towards North

4 0
3 years ago
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