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Natasha_Volkova [10]
3 years ago
7

Help me i have little time left i will give brainliest

Physics
1 answer:
eimsori [14]3 years ago
6 0

Answer:

Explanation:

Conservation of momentum

Initial momentum is zero

3.0(6.0) + 7.0v = 0

v = -18/7 = - 2.57142857...

|v| = 2.6 m/s

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Which example below provides a complete scientific description of an object in motion?
EastWind [94]

C. The marble moved 30 cm north in 6 seconds.

This gives a scientific or correct value of object in motion among all other options.

<em>-</em><em> </em><em>BRAINLIEST</em><em> answerer</em>

7 0
3 years ago
Read 2 more answers
What is the potential energy of two charges of +4.6 μC and +1.0 μC that are separated by a distance of 10.0 cm?
Artist 52 [7]

Answer:

U = 0.413 J

Explanation:

the potential energy between two charges q1 and q2 is given by the following formula:

U=k\frac{q_1q_2}{r}    (1)

k: Coulomb's constant = 8.98*10^9 NM^2/C^2

q1: first charge = 4.6 μC = 4.6*10^-6 C

q2: second charge = 1.0 μC*10^-6 C

r: distance between charges = 10.0 cm = 0.10 m

You replace the values of all variables in the equation (1):

U=(8.98*10^9Nm^2/C^2)\frac{(4.6*10^{-6}C)(1.0*10^{-6}C)}{0.10m}=0.413\ J

Hence, the energy between charges is 0.413 J

3 0
3 years ago
A 95kg fullback (football player for those not into sports) moving south with a speed of 5.0 m/s has a perfectly inelastic colli
Lunna [17]

Answer:

a.  v=3.11mls, 29.4^{0}

b.   K.E =-697.8J

Explanation:

To calculate the values in the  question, a deep understanding of perfect inelastic collision is important.

When two bodies undergo inelastic collision, two important parameters must be well understood i.e

Momentum: the momentum is always conserved in perfectly inelastic collision. i.e the total momentum after collision is the sum of the individual momentum before collision

Kinetic energy: Kinetic energy is not conserved due to dissipative force.

a.To calculate the velocity, we first find the total momentum before collision

Momentum of player 1 p_{1} =mv=95kg*5m/s\\p_{1} =475kgm/s\\

Momentum of player 2 p_{2} =mv=90kg*3m/s\\p_{1} =270kgm/s\\

Hence the total momentum p_{12}=p_{1}+p_{2}\\

Note, since the direction of movement before collision is due south and  due north respectively we have to represent the velocity using the rectangular coordinate

Hence  p_{12}=(m_{1}+m_{2})v=p_{1}i+p_{2}j\\

(95+90)v=475i+270j\\

v=2.57i+1.45j\\

solving for the resultant velocity, we have

v=\sqrt{2.75^{2} +1.45^{2}}\\ v=3.11mls

To calculate the direction of movement, we have

\alpha =tan^{-1}=\frac{v_{j} }{v_{i}}\\  \alpha =tan^{-1}=\frac{1.45}{2.57}\\\alpha =29.4^{0}

b. to calculate the decrease in total kinetic energy, before collision, the total kinetic was

K.E_{initial} =\frac{1}{2}m_{1}v_{1}^{2}+\frac{1}{2}m_{2}v_{2}^{2}.\\K.E_{initial} =((1/2)*95*5^{2})+((1/2)*90*3^{2})\\K.E_{initial} =1187.5+405\\K.E_{initial} =1592.5J\\

And the final kinetic energy after collision is

K.E_{final} =\frac{1}{2}(m_{1}+m_{2} )v^{2}\\  K.E_{final} =\frac{1}{2}(95+90)* 3.11^{2}\\ K.E_{final} =894.7J

The decrease in Kinetic energy is

K.E =K.E_{final}- K.E_{initial}=894.7-1592.5

K.E =-697.8J

The negative sign indicate a decrease in Kinetic energy

4 0
3 years ago
How tall would a tower need to be if the period of a pendulum were 30. seconds
Virty [35]
We use the following expression

T = 2*pi *sqrt(l/g)

Where T is the period of the pendulum

l is the length of the pendulum

and g the acceleration of gravity

We solve for l

l = [T/2*pi]² *g = [30s/2*pi]²* 9.8 [m/s²] = 223.413 m

The tower would need to be at least 223.413 m high
4 0
3 years ago
A child pushes a 75 N toy car across the floor. What is the mass of the car?
GaryK [48]

Answer:

7.6 kg

Explanation:

w=75N

w=mg

m=w÷g

m=75÷9.8

m=7.6kg

8 0
3 years ago
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