If you roast a marshmallow is it a chemical or physical change

A recipe for candy requires that the liquid ingredients be stirred constantly until the liquid reaches a temperature of 140°C.

A cylindrical fishing reel has a mass of 0.634 kg and a radius of 3.9 cm. A friction clutch in the reel exerts a restraining torque of 1.52 N · m if a fish pulls on the line.

A student increases the temperature of a 300 cm^3 balloon from 30c to 60c. what will the new volume of the ballon be

Two climbers are on a mountain. Simon, of mass m, is sitting on a snow covered slope that makes an angle θ with the horizontal. The coefficient of static friction between his body and the snow is μ.

A 250 mL sample of nitrogen (N2) has a pressure of 745 mm Hg at 30 C. What is the mass of nitrogen?

As part of his meal, a workman has a cup containing a hot drink. In order to keep the drink hot whilst he eats the rest of his meal, he covers the cup, as shown in the figure. Which sources of energy loss does this action reduce? Tick two boxes.

When energy is transformed, the amount of usable energy?

If an object weighs 39.2 n on earth, what is its mass

What happens when pressure is applied to a solid.

A box of mass 1 kg is hung from a spring scale. The reading on the spring scale is approximately 10N. What would be the reading on the spring scale if a box of mass 5 kg is hung from it? (Assume acceleration due to gravity to be 10 m/s2.