A ballon which always remain spherical, has a variable diameter . Determine the rate of charge of its volume with respect to x.

The radius of a circle is increasing at 0.7 cm/sec. What is the rate of increase of its circumference when r = 4.9 cm?

The radius of a circle is increasing uniformly at the rate of 4 cm per second Find the rate at which the area of the circle is increasing when the radius is 8 cm.

The radius of a circle is increasing uniformly at the rate of 3 cm per second. Find the rate at which the area of the circle is increasing when the radius is 10 cm.

15. A car starts from a point P at time t = 0 seconds and stops at point Q. The distance x, in metres, covered by it, in t seconds is given by

Find the time taken by it to reach Q and also find distance between P and Q.

A stone is dropped into a quiet lake and waves move in circles at a speed of 4 cm per second. At the instant when the radius of the circular waves is 10 cm, how fast is the enclosed area increasing?

The radius of a balloon is increasing at the rate of 10 cm per second. At what rate is the surface area of the balloon increasing when its radius is 15 cm?

The radius of an air-bubble is increasing at the rate of  At what rate is the volume of the bubble increasing when the radius is 1 cm?

An edge of a variable cube is increasing at the rate of 3 cm per second. How fast is the volume of the cube increasing when edge is 10 cm long?