Answer:
C. At a particular instant
Explanation:
Speed is the defined as the ratio between the distance covered by an object and the time taken:

where d is the distance and t the time.
However, there are two possible measurements of speed:
- Average speed: this is the speed measured over a non-zero time interval (for example: a car moving 100 metres in 5 seconds; its average speed is

- Instantaneous speed: this is the speed of an object measured at a particular instant in time, so for a time interval that tends to zero. So, in the previous example, the average speed is 20 m/s but the instantaneous speed of the car at various instants of time can be different from that value.
Answer:
0.686 g of ice melts each second.
Solution:
As per the question:
Cross-sectional Area of the Copper Rod, A = 
Length of the rod, L = 19.6 cm = 0.196 m
Thermal conductivity of Copper, K = 
Conduction of heat from the rod per second is given by:

where
= temperature difference between the two ends of the rod.
Thus

Now,
To calculate the mass, M of the ice melted per sec:

where
= Latent heat of fusion of water = 333 kJ/kg

<span>The answer is a heterogeneous mixture. Mixtures can be homogeneous and heterogeneous. If a solid and a liquid of a mixture cannot be separated and the difference between them is not visible, it is called homogeneous mixture (or solution). If a solid and a liquid of a mixture are visible and can be separated easily, the mixture is called heterogeneous.</span>
Answer: 12,600,000Cm
Explanation:
From the data's;
Charges(q) = 1.8 PC equal to 1.8 x 10^¹²C
Distance = 7 micrometer, is equal to 0.0000070m
From the equation of electric dipole moment, p= q x d, where q= charge, d=distance and p is the dipole moment.
Then we have 1.8x10^¹² x 0.0000070= 12,600,000Cm
NB: The charges are identical.