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viva [34]
3 years ago
13

An arrow of mass 0.5kg so it has 25J of kinetic energy; find the speed of the arrow v = m/s​

Physics
1 answer:
miss Akunina [59]3 years ago
4 0

Answer:

10 m/s

Explanation:

Use the kinetic energy formula:

KE=(1/2)mv^2

I always remember it as Kevin is half-mad, and very square.

25J = (1/2)*0.5kg*(v^2)

50J = 0.5kg*(v^2)

100J = v^2

v = 10 m/s

Check it:

KE = (1/2)*0.5*(10^2)

KE = 25J

yep, it's right!

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Model the concrete slab as being surrounded on both sides (contact area 24 m2) with a 2.1-m-thick layer of air in contact with a
Sloan [31]

Answer:

\dot{Q} =1.5\ W

Explanation:

Given that:

  • area of concrete slab, A=24\ m^2
  • thickness of the layer of air, dx=2.1\ m
  • temperature difference between the air and the concrete, dT=5\ K (\rm difference\ will\ be\ same\ in\ K\ and\ ^{\circ}C)

We have:

  • thermal conductivity of air at S.T.P., k=26.24 \times 10^{-3}\ W.m^{-1}.K^{-1}

<u>Now, according to Fourier's Law of conduction:</u>

\dot{Q} =k.A.\frac{dT}{dx}

putting the respective values:

\dot{Q} =26.24 \times 10^{-3}\times 24\times \frac{5}{2.1}

\dot{Q} =1.5\ W

5 0
3 years ago
A 2.00-kg object traveling east at 20.0 m/s collides with a 3.00-kg object traveling west at 10.0 m/s.
ELEN [110]
Momentum = mass x velocity

Before collision
Momentum 1 = 2 kg x 20 m /s = 40 kg x m/s
Momentum 2 = 3 kg x -10m/s = -30 kg x m/s

After collision
Momentum 1 = 2 kg x -5 m/s = -10 m/s
Momentum 2 = 3 kg x V2 = 3V2

Total momentum before = total momentum after
40 + -30 = -10 + 3V2
V2 = <span>6.67 m/s

Total kinetic energy before
</span><span>= (1/2) [ 2 kg * 20 m/s * 2 + 3 kg * ( -10 m/s) *2 ]
= 550 J
</span>
<span>Total kinetic energy after
</span>= (1/2) [ 2 kg * ( - 5 m/s) * 2 + 3 kg * 6.67 m/s *2 ]
= 91.73 J

Total kinetic energy lost during collision
=<span>550 J - 91.73 J
= 458.27 J</span>

8 0
3 years ago
Read 2 more answers
hot-air balloon is ascending at the rate of 14 m/s and is 84 m above the ground when a package is dropped over the side. (a) How
timurjin [86]

Answer:

a) t = 4.14 s

b) Speed with which it hits the ground = 40.58 m/s

Explanation:

Using the equations of motion,

g = 9.8 m/s², y = H = 84 m,

Initial velocity, u = 0 m/s,

final velocity, v = ?

Total Time of fall, t = ?

a) y = ut + gt²/2

84 = 0 + 9.8t²/2

4.9t² = 84

t² = 84/4.9

t = 4.14 s

b) v = u + gt

v = 0 + (9.8 × 4.14)

v = 40.58 m/s

4 0
3 years ago
Read 2 more answers
A 600-kg car traveling at 30.0 m/s is going around a curve having a radius of 120 m that is banked at an angle of 25.0°. The coe
ikadub [295]

Answer:

f_{fr}=1590.85 N

Explanation:

Here the total force at the horizontal components will be equal to the centripetal force on the car. So we will have:

f_{fr}cos(25)+Nsin(25)=m\frac{v^{2}}{r} (1)

  • f(fr) is the friction force
  • N is the normal force

Now, the sum of forces at the vertical direction is equal to 0.

Ncos(25)-mg-f_{fr}sin(25)=0 (2)          

Let's combine (1) and (2) to find f(fr)

f_{fr}=\frac{(mv^{2}/r)-mgtan(25)}{cos(25)+tan(25)sin(25)}

f_{fr}=\frac{(600*30^{2}/120)-600*9.81*tan(25)}{cos(25)+tan(25)sin(25)}  

f_{fr}=1590.85 N

I hope it helps you!

5 0
3 years ago
Which of the following are true? Select all that apply. The net electric field at any location inside a block of copper is zero
Agata [3.3K]

Answer:

1) The net electric field at any location inside a block of copper is zero if the copper block is in equilibrium.

2) In equilibrium, there is no net flow of mobile charged particles inside a conductor.

3) If the net electric field at a particular location inside a piece of metal is not zero, the metal is not in equilibrium.

Explanation:

1) and 3) A block of copper is a conductor. The charged particles on a conductor in equilibrium are at rest, so the intensity of the electric field at all interior points of the conductor is zero, otherwise, the charges would move resulting in an electric current.

2) The charged particles on a conductor in equilibrium are at rest.

6 0
3 years ago
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