What role does specific heat play in keeping a watermelon cool for a long time after removing it from a fridge on a hot day? `(AS_7)`

Take out a cooled bottle of water from refrifgerator and keep it on aa table. After some time you notice a droplets of water around it.Why?

A steel tape Im long is correctly calibrated for a temperature of 27.0 ^(@) C . The length of a steel rod measured by this tape is found to be 63.0 cm on a hot day when the temperature is 45.0^(@) C .What is the actual length of the steel rod on that day? What is the length of the same steel rod on a day when the temperature is 27.0^(@) C ? Coefficient of linear expansion of steel = 1.20 xx 10^(-5) K^(-1) .

To find the image - distance for varying object - distance in the case of a convex lens, a student obtains on screen a sharp image of a bright object placed very far from the lens. After that the gradually moves the object towards the lens and each time focuses its image on the screen. (a) In which direction - towards or away from the lens, does he move the screen to focus the object ? (b) What happens to the size of the image - Does it increase or decrease ? (c ) What happens when he moves the object very close to the lens ? (d) What happens to the intensity of the image as the object moves farther and farther away from the convex lens ?

(a) Estimate the speed with which electrons emitted from a heated emitter of an evacuated tube impinge on the collector maintained at a potential difference of 500 V with respect to the emitter. Ignore the small initial speeds of the electrons. The specific charge of the electron, i.e., its e/m is given to be 1.76 xx 10^(11) C kg^(-1) . (b) Use the same formula you employ in (a) to obtain electron speed for an collector potential of 10 MV. Do you see what is wrong ? In what way is the formula to be modified?