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andre [41]
3 years ago
8

Peter, a 100 kg basketball player, lands on his feet after completing a slam dunk and then immediately jump up again to celebrat

e his basket. When his feet first touch the floor after the dunk,
his velocity is 5 m/s downward; when his feet leave the floor 0.50 s later, as he jumps back up,
his velocity is 4 m/s upward. What is the average reaction force exerted upward by the floor on Peter during this 0.50 s?
Physics
1 answer:
Ludmilka [50]3 years ago
6 0

Answer:

1800 N

Solution:

Impulse = mΔv = m * (u - v) .

 here m = 100 kg

          u = 4 m/s

          v = -5 m/s

  impulse = 100 x ( 4 - ( -5 ) ) = 900 Kg m/s .

Average reaction Force ( Favg ) = impulse / Δt

Average reaction Force ( Favg )  = 900kg·m/s / 0.5s

Average reaction Force ( Favg )  = 1800 N

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A 65-kg ice skater stands facing a wall with his arms bent and then pushes away from the wall by straightening his arms. At the
Marrrta [24]

Our values can be defined like this,

m = 65kg

v = 3.5m / s

d = 0.55m

The problem can be solved for part A, through the Work Theorem that says the following,

W = \Delta KE

Where

KE = Kinetic energy,

Given things like that and replacing we have that the work is given by

W = Fd

and kinetic energy by

\frac {1} {2} mv ^ 2

So,

Fd = \frac {1} {2} m ^ 2

Clearing F,

F = \frac {mv ^ 2} {2d}

Replacing the values

F = \frac {(65) (3.5)} {2 * 0.55}

F = 723.9N

B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.

6 0
3 years ago
In a lab, four balls have the same velocities but different masses.
olya-2409 [2.1K]

Answer:

New Momentum of Ball B=13.2 \frac{\mathrm{kgm}}{\mathrm{s}}

<u>Explanation:</u>

Given:

Mass of Ball A=1kg

Mass of Ball B= 2kg

Mass of Ball C=5kg

Mass of Ball D=7kg

Velocities of A=B=C=D=2.2\frac{m}{s}

Momentum of Ball A=2.2\frac{k g m}{s}

Momentum of Ball B=4.4 \frac{k g m}{s}

Momentum of Ball C=11\frac{k g m}{s}

Momentum of Ball D=15\frac{k g m}{s}

To Find:

Change in Momentum When of Ball B gets tripled

Solution:

Though all balls have same velocity, thus we get

Velocities of A=B=C=D=2.2\frac{m}{s}

Initial Momentum of Ball B=4.4\frac{k g m}{s}

If the Mass of Ball B gets tripled;

We get New Mass of Ball B=3×Actual Mass of the ball

                                            =3×2=6kg

Thus we get Mass of Ball B=6kg

According to the formula,  

Change in momentum of Ball B \Delta p=m \times \Delta v

Where \Delta p=change in momentum

          m=mass of the ball B

         \Delta v=change in velocity ball B

And \Delta v=v, since all balls, have same velocity

Thus the above equation, changes to

         \Delta p=m \times v

Substitute all the values in the above equation we get

         \Delta p=6 \times 2.2

                     =13.2 \frac{\mathrm{kgm}}{\mathrm{s}}  

Result:

 Thus the New Momentum of ball B=13.2 \frac{\mathrm{kgm}}{\mathrm{s}}

3 0
3 years ago
Read 2 more answers
A Honda Hawk motorcycle and its rider with a combined mass of 450 kg travels around a curve of radius 106 m with a speed of 18 m
umka21 [38]

Answer: coefficient of static friction

= 0.31

Explanation: Since they negotiate the curve without skidding, the frictional force (F1) equals the centripetal force (F2).

F1= uN

F2 = M*(v²/r)

M is the combined mass 450kg

V is the velocity 18m/s

r is the radius 106m

N is the normal reaction 4410N

u is the coefficient of static friction

Making u subject of the formula we have that,

u = {450*(18²/106)} /4410

=1375.47/4410

=0.31

NOTE: coefficient of friction is dimensionless. It as no Unit.

7 0
2 years ago
Name three types of energy that exist in a large piece of charcoal on a grill in the sunlight. Explain why the charcoal has each
qaws [65]

Answer:

A large piece of charcoal on a grill in the sunlight (if it's burning) will consist of the following types of energy:

  1. Chemical
  2. Heat and
  3. Light

Explanation:

Charcoal is basically carbon which is produced when wood is heated strongly in the absence of oxygen. From a chemistry point of view, charcoal contains combustible carbon whose chemical formula is C. Sometimes, H_{2}O which is water may be found in it but in very small units.

All matter contains Heat energy. Charcoal is not an exception. As the charcoal burns, the heat energy is produced along with Light energy.

Light comes in many forms such as Infrared rays, Xrays, Visible Spectrum light, etc.

The glow which the coal gives off fall under the visible spectrum of light.

Cheers

8 0
2 years ago
Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when
Lelechka [254]

Answer:

option b

Explanation:

the heavier one will have twice the kinetic energy of the lighter one

5 0
3 years ago
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