Answer:
D.
R increases
V is constant
I decreases
Explanation:
The resistance of a wire is given by the following formula:
It is clear from this formula that resistance is directly proportional to the length of wire. So, when length of wire is increased, <u>the resistance of circuit increases</u>.
The <u>voltage in the circuit will be constant</u> as the voltage source remains same and it is not changed.
Now, we can use Ohm Law:
V = IR
at constant V:
I ∝ 1/R
it means that current is inversely proportional to resistance. Hence, the increase of resistance causes <u>the current in circuit to decrease.</u>
Therefore, the correct option will be:
<u>D.</u>
<u>R increases
</u>
<u>V is constant
</u>
<u>I decreases</u>
Object will only form shadow if it won't reflect light.
That is, stone will form shadow as it reflects light.
Hope this helps you.
The correct answer to the question will be D. a skydiver whose air resistance is equal to that of her weight.
EXPLANATION:
As per the first option, the point is situated outside of the spinning top whose rotational speed is constant. When a body moves in a circular path, its direction is always changed which produces an acceleration. The point present outside of the spinning top moves in a circular path. Hence, it experiences an acceleration.
As per the second option, the car on the freeway is experiencing a net force of -120 N. Here, the car experiences negative acceleration which opposes the motion.
As per the third option, a submerged beach ball whose buoyant force is eight times the force of gravity. Hence, there is net force on the submerged beach ball which will push the ball upward. Hence, the ball experiences an acceleration.
The third option is that the skydiver whose air resistance is equal to that of her weight. Here, the weight of the driver acts in vertical downward direction while air resistance acts in vertical upward direction. The net force acting on the driver is zero. Hence, the acceleration of the driver is zero.
<span>Answer:
Yes, I get 17 rad/s², too.
Note that the assumption of constant angular acceleration is really, really, terrible. A valid answer to this question (i.e., one that does not assume constant angular acceleration) involves differential equations. But if you do assume constant angular acceleration, this is quite straightforward. Use constant-acceleration kinematics:
Δθ = ω_i Δt + ½α (Δt)²
You know the pencil moves through an angle of π/2 radians. The initial angular velocity is zero. You already found the angular acceleration, and you want Δt.
Δt = âš[ 2 Δθ / α ] = âš[ 2 (Ď€/2 rad) / 17 rad/s² ] = 0.34 s
This is the same calculation oldprof makes, but his treatment of the pencil as a point mass rather than a uniform rod has thrown his angular acceleration off.</span>