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faust18 [17]
3 years ago
5

A block of mass 21 kg slides up a frictionless plane inclined at 13◦ with the horizontal under the influence of a force of 210 N

acting parallel to the incline and up the incline. The acceleration of gravity is 9.8 m/s 2 . What is the acceleration of the block? Answer in units of m/s 2 .
Physics
1 answer:
svetlana [45]3 years ago
3 0

Answer:

a= 8.74 m/s²

Explanation:

Given that

m = 21 kg

θ = 13◦

F= 210 N

g= 9.8 m/s²

The force due to gravity

F₁= m g sinθ

F₁=12 x 9.8 x sin 13◦

F₁=26.45 N

Lets take acceleration is a  m/s²

Form Newtons second law

F - F₁ = m a

210 - 26.45 = 21 x a

a= 8.74 m/s²

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A resistor with resistance R and an air-gap capacitor of capacitance C are connected in series to a battery (whose strength is "
blsea [12.9K]

Answer:

a) Q = C*emf

b)  Reduction in electric field strength and electric potential

c) Initial current through the resistor = emf/R

d) The final charge = K*C*emf

Explanation:

a) The resistors and capacitors are connected in series with the battery

Using Kirchoff's voltage law, sum of all voltages in the circuit is zero

Let V_{R} = Voltage dropped across the Resistor

V_{c} = Voltage dropped across the capacitor

Applying KVL;

emf - V_{R}  - V_{c} = 0\\.........................(1)

Since the connection is in series, the same current flow through the circuit

V_{R} = IR\\Q = CV_{c} \\V_{c} = Q/C

Putting V_{c} and V_{R} into equation (1)

emf - IR - Q/C = 0

At the final charge, the capacitor in fully charged, and current drops to zero due to equilibrium

I = 0A\\emf = Q/C\\Q = C* emf

b) Current starts running through the plate because as the sheet of plastic is inserted between the plates both the electric field intensity and the electric potential reduces. The charge also reduces, then current flows

c) The current through the resistor is the current through the entire circuit ( series connection)

I = I_{o} \exp(\frac{-t}{RC} )\\At time the initial time, t\\t = 0\\ I_{o} = \frac{emf}{R} \\

Putting the values of t and I₀ into the formula for I written above

I = \frac{emf}{R} \exp(0)\\I = \frac{emf}{R}

d) NB: The initial charge on the capacitor = C * emf

The final charge will be:

Q = K* Q_{initial} \\Q_{initial}  = C *emf\\Q_{final}  = KCemf

4 0
3 years ago
A 5. 3 ft -ft-tall girl stands on level ground. The sun is 30 ∘ above the horizon. How long is her shadow?
slamgirl [31]

The trigonometric ratios are sine, cosine and tangent. We can use cosine to find the length of the shadow from the calculation as 1.7 ft.

<h3>What is trigonometric ratio?</h3>

The term trigonometric ratio has to do with sine, cosine and tangent which are used to solve problems that involve the right angled triangle.

Using the geometry of the right angle triangle, we can find the tangent of the angle 30 in order to obtain the length of the shadow.

Tan 30° = opp/3

opp = 3Tan 30°

opp = 1.7 ft

The length of the girl's shadow from the calculation is 1.7 ft.

Learn more about tangent: brainly.com/question/14022348

8 0
2 years ago
Q1.
Vesnalui [34]

Answer:

P = 450 J

Explanation:

Given that,

Mass of a child, m = 18 kg

The vertical distance from the top to the bottom of the slide is 2.5 metres.

The Gravitational field strength = 10 N/kg

We need to find the decrease in gravitational potential energy of the child sliding from the  top to the bottom of the slide.

The formula for the gravitational potential energy is given by :

P = mgh

Substituting all the values,

P = 18 kg × 10 m/s² × 2.5 m

P = 450 J

Hence, the decrease in gravitational potential energy is 450 J.

4 0
2 years ago
How much work is accomplished when a force of 250 N pushes a box across the floor for a distance of 50 meters?
IrinaK [193]
Work = force * distance
and newton*meters = Joule

In this case,  work = 250N*50m = 12500 J

So the answer is D) 12,500 J

3 0
3 years ago
What is the force needed to give a .25 kg arrow an acceleration of 196m/s2?
Rzqust [24]
<span>49N is the force needed to give a .25 kg arrow an acceleration of 196m/s2. F =ma ⇒ =( 0.25kg)(196m/s2) = 49N if the arrow is shot horizontally where the applied force is entirely in the x-direction.</span>
5 0
2 years ago
Read 2 more answers
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