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puteri [66]
4 years ago
6

A car is driving 25.5 m/s when it hits

Physics
1 answer:
IceJOKER [234]4 years ago
6 0

Answer:

it takes the car 4.362 seconds to cover the distance of 88.4 m.

Explanation:

The distance the car covers is given by the function

x(t) = vt-\dfrac{1}{2}at^2,

where v = 25.5m/s , and a = 2.40m/s, putting  these in we get:

x(t) = 25.5t-\dfrac{1}{2}(2.4)t^2\\\\x(t) = 25.5t-1.2t^2

Now, when the car has moved to 88.4m, x(t) = 88.4 , or

x(t) = 25.5t-1.2t^2 = 88.4

which is a quadratic equation with solutions

t = 4.362s,\\t = 16.887s

We take the first solution t = 4.362s, <em>since at that time the car is still moving right and decelerating</em>. The second solution t =16.887 describes the situation where the car has stopped decelerating and is now moving leftwards because the decelerating is leftwards, <em>which is utterly wrong because we know that cars do not start moving backwards after the brakes have stopped them! </em>

Thus, it takes the car 4.362 seconds to cover the distance of 88.4 m.

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The lawn sprinkler consists of four arms that rotate in the horizontal plane. The diameter of each nozzle is 8 mm, and the water
sashaice [31]

Answer: the constant angular velocity of the arms is 86.1883 rad/sec

Explanation:

First we calculate the linear velocity of the single sprinkler;

Area of the nozzle = π/4 × d²

given that d = 8mm = 8 × 10⁻³

Area of the nozzle = π/4 × (8 × 10⁻³)²

A = 5.024 × 10⁻⁵ m²

Now total discharge is dived into 4 jets so discharge for single jet will be;

Q_single = Q / n = 0.006 / 4 = 1.5 × 10⁻³ m³/sec

So using continuity equation ;

Q_single = A × V_single

V_single = Q_single/A

we substitute

V_single = (1.5 × 10⁻³) / (5.024 × 10⁻⁵)

V_single = 29.8566 m/s

Now resolving the forces as shown in the second image,

Vt = Vcos30°

Vt = 29.8566 × cos30°

Vt = 25.8565 m/s

Finally we calculate the angular velocity;

Vt = rω

ω_single = Vt / r

from the given diagram, radius is 300mm = 0.3m

so we substitute

ω_single = 25.8565 / 0.3

ω_single = 86.1883 rad/sec

Therefore the constant angular velocity of the arms is 86.1883 rad/sec

7 0
3 years ago
A fixed electric space heater wired by a cable with an ampacity of 30 A should draw a maximum current of A. 30 A. B. 24 A. C. 15
Nookie1986 [14]

Answer: The correct answer is option (A).

Explanation

Ampacity is defined as the maximum amount of the current carried by the conductor continuously without exceeding its temperature rating.

The ampacity of the wire of the heater is 30 A .And this means that wire is capable of conducting current of maximum amount of 30 Ampere through it without exceeding its temperature rating.

Hence, the correct answer is option is (A).

7 0
3 years ago
Metal sphere A has a charge of − Q . −Q. An identical metal sphere B has a charge of + 2 Q . +2Q. The magnitude of the electric
Goshia [24]

Complete Question:

Metal sphere A has a charge of − Q . −Q. An identical metal sphere B has a charge of + 2 Q . +2Q. The magnitude of the electric force on sphere B due to sphere A is F . F. The magnitude of the electric force on sphere A due to sphere B must be:

A. 2F

B. F/4

C. F/2

D. F

E. 4F

Answer:

D.

Explanation:

If both spheres can be treated as point charges, they must obey the Coulomb's law, that can be written as follows (in magnitude):

F =\frac{kQ*2Q}{r^{2} }

As it can be seen, this force is proportional to the product of the charges, so it must be the same for both charges.

As this force obeys also the Newton's 3rd Law, we conclude that the magnitude of the electric force on sphere A due to sphere B, must be equal to the the magnitude of the force on the sphere B due to the sphere A, i.e., just F.

3 0
3 years ago
2. A stone is thrown horizontally at a speed of 6.0 m/s from the top of a cliff 78.4 m high.
Ostrovityanka [42]

Answer:

a) 8 seconds if you are using earth's gravity.

b) 48m if the velocity does not change

c) 9.8m/s

Explanation:

3 0
3 years ago
What is the relationship between the type of energy sublevels present and the
ziro4ka [17]
Each principal energy level has one sublevel containing one orbital, an s orbital, that can contain a maximum of two electrons. Electrons in this orbital are called s electrons and have the lowest energy of any electrons in that principal energy level.
6 0
3 years ago
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