Aball at the end of a string is whirled in a horizontal circle. if it takes 2 seconds to make a revolution and the strong length is 2 m , how fast is the ball moving ? how much is it being accelerated

You can calculate the speed of the ball by the distance it travels divided by the time.

Length of string = 2m

Circumference of circle = 2*radius*π = 4*pi = ~12.6 meters

Speed = distance/time = 12.6m/2s = 6.28m/s

Acceleration = V²/R where the velocity at any one point is the same as the speed.

acceleration = (6.28)²/2 = ~19.72m/s²

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s