Part A: -,+
The elevator descends, dictating the velocity's direction, which aligns with the movement's path. With the positive direction defined as upward, the velocity is negative. After the emergency button is pressed, the elevator begins to stop, indicating that the velocity is decreasing. Therefore, the acceleration is oriented in the opposite way to the velocity, making its sign +.
Part B: +, -
The ball ascends, which determines the positive direction of the velocity. Hence, the velocity is positive.
Once the ball is thrown, the only force acting on it is gravity, opposing the ball’s ascent and causing it to descend. This means the acceleration is directed downwards, resulting in a negative sign.
Part C: 0, -
Throughout the ball's trajectory from the moment it's thrown until it drops to the ground, gravity constantly exerts downward acceleration (-).
After the throw, the ball's velocity will decline due to gravity. When it reaches a velocity of 0, it achieves its peak height. At this specific moment, the ball begins to descend again under the influence of gravity. However, at the peak height, the ball's velocity is 0.
Answer:
A. 2.57 K
Explanation:
Using the specific heat capacity,
Q = cmΔT........................ Equation 1
Where Q = Heat energy absorbed by silver, m = mass of silver, c = specific heat capacity for silver, ΔT = temperature change of the silver.
Rearranging gives ΔT as the subject of the equation
ΔT = Q/cm................... Equation 2
Provided: Q = 300 J, m = 500 g = 0.5 kg
Constant: c = 233 J/kg.K
Inserting values into equation 2 yields
ΔT = 300/(0.5×233)
ΔT = 300/116.5
ΔT = 2.57 K
Therefore, the correct answer is A. 2.57 K
Response:
Details:
Utilizing Faraday's Newmann Lenz law enables the assessment of the induced emf within the loop:
where:
represents the change in magnetic flux
symbolizes the change over time.
#The magnetic flux linked to the coil can be represented as:
Where:
N represents the number of loops.
A denotes the area for each loop (
).
B indicates the strength of the magnetic field.
represents the angle between the magnetic field direction and the normal to the loop's area.
=0.0250T/s is indicated as the rate of magnetic field increase.
#Plugging in values into the emf equation:
Thus, the induced emf is
When an electric dipole is subjected to an electric field, it experiences a torque given by the equation torque = p x E = p E sinθ, where θ represents the angle between p and E. The torque will be zero when θ equals 0, aligning both p and E, which is a stable orientation. If θ is 180°, the torque also equals zero since p and E point in opposite directions, representing an unstable orientation because even a slight deflection will revert to the stable position due to torque from the electric field.
