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3 years ago

If the current is cut in half and the resistance is increased by a factor of three, how will the power be affected?

1 answer:

8 0

One formula for the power dissipated in an electric circuit is

   Power = (current)² x (resistance) .

I think that's the one we should use, because it has exactly
all of the quantities that we know or need to find.

OK.
   Original power = (original current)² x (original resistance)
and
   New power = (new current)² x (new resistance)

   = (0.5 x old current)² x (3 x old resistance)

   = (0.25) (old current)² x (3) (old resistance)

   = (0.75) (original current)² (original resistance)

   = (0.75) (original power) .

Summary: New power = (0.75) (original power)

That looks just like
choice B:
   The power will decrease to 75 percent of its previous value.

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A ranger in a national park is driving at 56 km/h when a deer jumps onto the road 65 m ahead of the vehicle. After a reaction ti

vagabundo [1.1K]

Answer:

t = 1.58 s

Explanation:

given,

Speed of ranger, v = 56 km/h

v = 56 x 0.278 = 15.57 m/s

distance, d = 65 m

deceleration,a = 3 m/s²

reaction time = ?

using stopping distance formula

$d = v. t + \dfrac{v^2}{2a}$

$t = \dfrac{d}{v} -\dfrac{v}{2a}$

t is the reaction time

$t = \dfrac{65}{15.57} -\dfrac{15.57}{2\times 3}$

t = 1.58 s

hence, the reaction time of the ranger is equal to 1.58 s.

3 0

3 years ago

Trumpeter A holds a B-flat note on the trumpet for a long time. Person C is running towards the trumpeter at a constant velocity

denpristay [2]

Answer:

Person B

Explanation:

Person B will hear the frequency that is lower than the B- flat.

5 0

3 years ago

Read 2 more answers

A girl exerts a horizontal force of 109 N on a crate with a mass of 31.2 kg. HINT (a) If the crate doesn't move, what's the magn

vesna_86 [32]

Answer:

(a) Magnitude of static friction force is 109 N

(b) Minimum possible value of static friction is 0.356

Solution:

As per the question;

Horizontal force exerted by the girl, F = 109 N

Mass of the crate, m = 31.2 kg

Now,

(a) To calculate the magnitude of static friction force:

Since, the crate is at rest, the forces on the crate are balanced and thus the horizontal force is equal to the frictional force, f:

F = f = 109 N

(b) The maximum possible force of friction between the floor and the crate is given by:

$f_{m} = \mu_{s}N$

where

N = Normal reaction = mg

Thus

$f_{m} = \mu_{s}mg$

For the crate to remain at rest, The force exerted on the crate must be less than or equal to the maximum force of friction.

$f\leq f_{m}$

$f \leq \mu_{s}mg$

$109 \leq \mu_{s}\times 31.2\times 9.8$

$\mu_{s}\geq 0.356$

7 0

2 years ago

Explain why you cannot use mass or volume alone to identify substances.

Alex17521 [72]

Objects can have the same mass (but different <span>compositions). Only mass or volume cannot tell you if the object is solid or vo</span>lumes) or same volume (but different masses)

4 0

3 years ago

A Nichrome wire 44 cm long and 0.30 mm in diameter is connected to a 3.1 V flashlight battery. What is the electric field inside

Alexeev081 [22]

Answer:

7.05 Volts/m

Explanation:

L = length of the Nichrome wire = 44 cm = 0.44 m

V = Potential difference across the end of the wire = battery voltage = 3.1 Volts

E = magnitude of electric field inside the wire

Magnitude of electric field inside the wire is given as

$E = \frac{V}{L}$

Inserting the values

$E = \frac{3.1}{0.44}$

E = 7.05 Volts/m

4 0

3 years ago