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3 years ago

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A 2.0-kg object moving with a velocity of 5.0 m/s in the positive x direction strikes and sticks to a 3.0-kg object moving with

a speed of 2.0 m/s in the same direction. How much kinetic energy is lost in this collision

1 answer:

Andrej [43]3 years ago

4 0

Answer:

5.4 J.

Explanation:

Given,

mass of the object, m = 2 Kg

initial speed, u = 5 m/s

mass of another object,m' = 3 kg

initial speed of another orbit,u' = 2 m/s

KE lost after collusion = ?

Final velocity of the system

Using conservation of momentum

m u + m'u' = (m + m') V

2 x 5 + 3 x 2 = ( 2 + 3 )V

16 = 5 V

V = 3.2 m/s

Initial KE = $\dfrac{1}{2}mu^2 + \dfrac{1}{2}m'u'^2$

= $\dfrac{1}{2}\times 2\times 5^2 + \dfrac{1}{2}\times 3 \times 2^2$

= 31 J

Final KE = $\dfrac{1}{2} (m+m')V^2 = \dfrac{1}{2}\times 5 \times 3.2^2 = 25.6 J$

Loss in KE = 31 J - 25.6 J = 5.4 J.

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Why do we consider eyes, ears, and fingers as physical sensor

seraphim [82]

Answer:

because

Explanation:

because we need eye to see if you don't have eyes how you regnise some one

if you have ears how can you know who's voice is who's

if don't have fingers how can you know what your are holding this is why they are called physical sensors

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3 years ago

Read 2 more answers

After an initial race George determines that his car loses 35 percent of its acceleration due to air resistance travelling at 38

ddd [48]

Answer:

64.2 m/s

Explanation:

We are given that

Speed ,v=38 m/s

We have to find the maximum speed when his car reach on flat ground.

Using dimensional analysis

$F_{res}\propto v^2$

If 35% acceleration reduced by F(res) at 38 m/s

Then, 100% acceleration can be reduced by F(res) at v' m/s

$\frac{F_1}{F_2}=\frac{v^2}{v'^2}$

$v'^2=\frac{F_2}{F_1}v^2$

$v'=v\sqrt{\frac{F_2}{F_1}}$

Substitute the values

$v'=38\times \sqrt{\frac{100}{35}}$

$v'=64.2 m/s$

Hence, the maximum speed when his car can reach on flat ground=64.2 m/s

3 0

2 years ago

A pendulum is made of a small sphere of mass 0.250 kg attached to a lightweight string 1.20 m in length. As the pendulum swings

olchik [2.2K]

Answer:

0.833 N

Explanation:

Formula for Kinetic Energy $E_k = \frac{mv^2}{2}$

Formula for Potential Energy $E_p = mgy$

First we need to find the vertical distance between the maximum-angle position and the pendulum lowest point:

Using the swinging point as the reference, the vertical distance from the maximum-angle (34 degree) position to the swinging point is:

$L * cos(34^o) = 1.2cos(34^o) = 1.2*0.83 = 0.995 \approx 1 m$

At the lowest position, pendulum is at string length to the swinging point, which is 1.2 m. Therefore, the vertical distance between the maximum-angle position and the pendulum lowest point would be

y = 1.2 - 1 = 0.2 m.

As the pendulum is traveling from the maximum-angle position to the lowest point position, its potential energy would be converted to the kinetic energy.

By law of energy conservation:

$E_k = E_p$

$\frac{mv^2}{2} = mgy$

$v^2 = 2gy$

$v = \sqrt{2gy}$

Substitute $g = 10 m/s^2$ and y = 0.2 m:

$v = \sqrt{2 * 10 * 0.2} = \sqrt{4} = 2 m/s$

At lowest point, pendulum would generate centripetal tension force on the string:

$F = m\frac{v^2}{L}$

We can substitute mass m = 0.25, rotation radius L = 1.2 m and v = 2 m/s:

$F = 0.25\frac{2^2}{1.2} = 0.833 N$

5 0

3 years ago

Which statement is correct? (a) Net force causes motion. (b) Net force causes change in motion. Explain your answer and give an

Valentin [98]

Answer:

(b) Net force causes change in motion.

Explanation:

There can be a motion even if there is no net force acting on an object.

It can be justified by giving an example:- when object is moving at constant speed then it has no net force and still is in motion.

If there is a net force acting, then the object will accelerate and this will cause change in motion.

The change in motion can be change in direction of motion, change in speed of motion.

For example when an object is moving in east direction if someone accelerate it this will result in change in motion or change in speed and after some time the net force is applies in the north direction then the object will move in the north direction which proves that the net force also causes change in direction.

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3 years ago

A flat screen TV uses 120 Watts. How much energy is used up if it is left on for 15 minutes? Question 25 options: 4 J 15 J 0.67

Natasha2012 [34]

Answer:

Option d (108,000 J) is the correct answer.

Explanation:

The given values are:

Power,

P = 120 Watts

Time,

t = 15 min.

i.e.,

= 900 sec

As we know,

⇒ $P=\frac{W}{t}$

So,

⇒ $W=P\times t$

On substituting the given values, we get

⇒ $=120\times 900$

⇒ $=108,000 \ J$

5 0

2 years ago