What are three elements that are in the same group

A 500 kg sack of coal falls vertically onto a 2000 kg railroad flatcar which was initially moving horizontally at 3 m/s. no exte

Zinaida [17]

Since there are no external forces, including friction, act on the flatcar. after the sack rests on the flatcar, we would assume that momentum is conserved. This means that

total momentum of car before collision = total momentum of car after collision.

Recall,

momentum = mass x velocity

From the information given,

mass of car before collision = 2000

velocity of car before collision = 3

Thus,

total momentum of car before collision = 2000 x 3 = 6000

Also,

mass of sack = 500

mass of car and sack after collision = 500 + 2000 = 2500

velocity after collision = v

momentum after collision = 2500 x v = 2500v

Since momentum is conserved, then

6000 = 2500v

v = 6000/2500

v = 2.4

the speed of the flatcar is 2.4 m/s

6 0

1 year ago

Identical isolated conducting spheres 1 and 2 have equal charges and are separated by a distance that is large compared with the

scoundrel [369]

Answer:

F = 0.1575 N

Explanation:

When the third sphere touches the first sphere, the charge is distributed between both spheres, then now the first sphere has only half of his original charge.

In this moment then

Sphere one has a charge = Q/2

Sphere three has a charge = Q/2

Now when the third sphere touches the second sphere again the charge is distributed in a manner that both sphere has the same charge.

How the total charge is Q = Q/2 + Q = 3/2Q, when the spheres are separated each one has 3/4Q

Sphere two has a charge = 3/4Q

Sphere three has a charge = 3/4Q

The electrostatic force that acts on sphere 2 due to sphere 1 is:

F = $\frac{kQ_{1}Q_{2} }{r^{2} }$

F= $\frac{K(Q/2)(3Q/4)}{r^{2} }$

how $\frac{KQ^{2} }{r^{2} }$ = 0.42

Then

F = $\frac{0.42*3}{8}$

F = 0.1575 N

3 0

3 years ago

A soccer player extends her lower leg in a kicking motion by exerting a force with the muscle above the knee in the front of her

lisabon 2012 [21]

Answer:

10.09 N

Explanation:

Analogously to Newton's second law, torque can be defined as:

$\tau=I\alpha$

Here, I is the moment of inertia and $\alpha$ is the angular acceleration. We have:

$\tau=(0.65kg*m^2)(29.5\frac{rad}{s^2})\\\tau=19.18N*m$

Torque is the vector product of the position vector of the point at which the force is applied by the force vector:

$\vec{\tau}=\vec{r}\times \vec{F}$

Since the effective lever arm is perpendicular to the force, the angle between them is $90^\circ$ . The magnitud of this vector product is defined as:

$\tau=rFsen\theta$ .

Solving for F and replacing the known values:

$F=\frac{\tau}{rsen\theta}\\F=\frac{19.18N*m}{1.9m(sen90^\circ)}\\F=10.09N$

8 0

3 years ago

6.

jolli1 [7]

Answer: PAPPER:D

Explanation:IM THE MYSTERY MAN WHOOSH??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

7 0

3 years ago

A power cycle operates between a lake’s surface water at a temperature of 300 K and water at a depth whose temperature is 285 K.

nikdorinn [45]

Answer: a) 0.04kW = 40W

b) 0.05

Explanation:

A)

Thermal efficiency of the power cycle = Input / output

Input = 10 kW + 14,400 kJ/min = 10 kW + 14,400 kJ/(60s) = 10 kW + 14,400/60 kW.

Output = 10 kW

Thermal Efficiency = Output / Input = 10kW / 250kW = 0.04KW = 40W

B)

Maximum Thermal Efficiency of the power cycle = 1 - T1/T2

Where T1 = 285kelvin

And T2 = 300kelvin

Maximum Thermal Efficiency = 1 - T1/T2 = 1 - 285/300 = 0.05

8 0

4 years ago

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