Answer:
a:it speed up
b:it should be positive since final
velocity is larger than initial velocity
c:acceleration is approximately 4.5
m/s^2
Explanation:
initial velocity=u=4.47m/s
Final velocity=v=17.9m/s
Time=t=3 seconds
a:the car speed up since the velocity
increased
b:change in velocity is positive
because final velocity is larger than
initial velocity
17.9-4.47=13.43 m/s
c: acceleration=(v-u)/t
acceleration=(17.9-4.47)/3
acceleration=13.43/3
acceleration=4.5 m/s^2
Explanation:
(a) From E=
r
2
k
e
Q
Q=
k
e
Er
2
=
(8.99×10
9
N⋅m
2
/C
2
)
(8.90×10
2
N/C)(0.750m)
2
=5.57×10
−8
C
But Q is negative since
E
→
points inward, so
Q=−5.57×10
−8
C=−55.7nC
(b) The negatve charge has a spherically symmetric charge distribution, concentric with the spherical shell
The power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
<h3>What is electrical power?</h3>
Electrical power is the rate at which electrical work is done.
- Electrical power = voltage × current
The LED is 75% efficient means that 75% of power dissipated by the LED is converted to light.
Total power dissipated = 5 × 2.5 = 12.5 Watts
- Work done = power × time (in seconds)
Work done = 12.5 × (1 × 3600 + 15 × 60)
Work done = 56250 J = 56.25 kJ
Therefore, the power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.
Learn more about electrical power and work done at: brainly.com/question/23901751
#SP1
Answer:
Explanation:
By conservation of energy, the sum of the kinetic and gravitational potential energies at the surface of the Earth must be equal than their sum at infinity, so we have:
Where 
is the gravitational constant,
and 
are the mass and radius of the Earth, <em>m </em>is the mass of the particle, 
its velocity at the surface of the Earth (which would be its escape velocity) and 
and 
are the velocities and distance at infinity, which would be null and infinity respectively, so the right hand side of our equation is 0J, which leaves us with:
Also, since the force the molecule experiments is the force of gravity (disregarding drag), we can write its weight in terms of Newton's Law of Gravitation:
Which means that:
So finally putting all together we can write:
