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stepladder [879]
3 years ago
5

A 2.0 kg mass moving at 5.0 m/s suddenly collides head-on with a 3.0 kg mass at rest. If the collision is perfectly inelastic, h

ow much kinetic energy was lost during the collision?
(a) 20 J
(b) 26 J
(c) 15 J
(d) 8 J
Physics
1 answer:
liberstina [14]3 years ago
4 0

Answer:

correct answer is (c) 15 J

Explanation:

given data

mass m1 = 2 kg

velocity V1 = 5 m/s

mass other  = 3 kg

so mass m2 = 2+ 3 kg = 5 kg

solution

we will apply here conservation of momentum:

m1V1 = m2V2  ..........................1

put here value and we get  velocity v2

(2.0) × (5.0) = (2.0 + 3.0) × V

solve it we get

10 = 5 × V 2

V2 = 2.0 m/s

so here kinetic energy will be

KE = ½ × m × v²

so

∆KE = ½ × m1 × (v1)²  -  ½  × m2 × (v2) ²

∆KE = 0.5 × 2 × 25 - 0.5 × 5 × 4

 ∆KE = 25 - 10

∆KE  = 15 J

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The ball drop 2kms in the air
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2 strings both vibrate at exactly 220 Hz. The tension in one of them is then decreased sightly. As a result, 3 beats per second
MAVERICK [17]

Explanation:

Given that,

2 strings both vibrate at exactly 220 Hz. The frequency of sound wave depends on the tension in the strings.

The tension in one of them is then decreased sightly, then f_2 will decrese.

Beat frequency, f=f_1-f_2

3=220-f_2

f_2=217\ Hz

So, the new frequency of the string is 217 Hz. Hence, this is the required solution.

3 0
3 years ago
How much heat is required to convert solid ice with a mass of 985 g and at a temperature of -29.5 °c to liquid water at a temper
liberstina [14]

Consider, please, this solution:

The final heat is:

Q=Q₁+Q₂+Q₃≈726.116 kJ

All the details are in the attachment.

6 0
3 years ago
Two objects (42.0 and 21.0 kg) are connected by a massless string that passes over a massless, frictionless pulley. The pulley h
Kazeer [188]

Answer:

a = 3.27 m/s²

T = 275 N

Explanation:

Given that:

Mass m₁ = 42.p0 kg

Mass m₂ = 21.0 kg

Consider both masses to be in a whole system, then:

The acceleration can be determined as:

(m_1+m_2)a = g(m_1-m_2)

Making acceleration the subject in the above formula;

a =\dfrac{g(m_1-m_2)}{(m_1+m_2)}

a =\dfrac{9.8(42.0-21.0)}{(42.0+21.0)}

a =\dfrac{9.8(21.0)}{(63.0)}

a =\dfrac{205.8}{(63.0)}

a = 3.27 m/s²

in the string, the tension is calculated using the formula:

T = \dfrac{2m_1m_2g}{(m_1+m_2)}

T = \dfrac{2(42)(21)(9.81)}{(42+21)}

T = \dfrac{17304.84}{63}

T = 274.68 N

T ≅ 275 N

8 0
3 years ago
Two runners start at the same point on a straight track. The first runs with constant acceleration so that he covers 98 yards in
charle [14.2K]

Answer:

94.13 ft/s

Explanation:

<u>Given:</u>

  • t = time interval in which the rock hits the opponent = 10 s - 5 s = 5 s
  • s = distance to be moved by the rock long the horizontal = 98 yards
  • y = displacement to be moved by the rock during the time of flight along the vertical = 0 yard

<u>Assume:</u>

  • u = magnitude of initial velocity of the rock
  • \theta = angle of the initial velocity with the horizontal.

For the motion of the rock along the vertical during the time of flight, the rock has a constant acceleration in the vertically downward direction.

\therefore y = u\sin \theta t +\dfrac{1}{2}(-g)t^2\\\Rightarrow 0 = u\sin \theta 5 +\dfrac{1}{2}(-9.8)\times 5^2\\\Rightarrow u\sin \theta 5 =\dfrac{1}{2}(9.8)\times 5^2......(1)\\

Now the rock has zero acceleration along the horizontal. This means it has a constant velocity along the horizontal during the time of flight.

\therefore u\cos \theta t = s\\\Rightarrow u\cos \theta 5 = 98.....(2)\\

On dividing equation (1) by (2), we have

\tan \theta = \dfrac{25}{20}\\\Rightarrow \tan \theta = 1.25\\\Rightarrow \theta = \tan^{-1}1.25\\\Rightarrow \theta = 51.34^\circ

Now, putting this value in equation (2), we have

u\cos 51.34^\circ\times  5 = 98\\\Rightarrow u = \dfrac{98}{5\cos 51.34^\circ}\\\Rightarrow u =31.38\ yard/s\\\Rightarrow u =31.38\times 3\ ft/s\\\Rightarrow u =94.13\ ft/s

Hence, the initial velocity of the rock must a magnitude of 94.13 ft/s to hit the opponent exactly at 98 yards.

3 0
3 years ago
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