A 20 g ball is fired horizontally with speed v0 toward a 100 g ball hanging motionless from a 1.0-m-long string. The balls un-dergo a head-on, perfectly elastic collision, after which the 100 g ball swings out to a maximum angle umax=50. What was v0?

7.93 m/s

Explanation:

Given

mass of ball

Mass of hanging ball

Length of string

Maximum angle turned

is the initial velocity of ball 1  and 0 is the initial  velocity of ball 2

For Perfectly elastic final velocity of ball 1 and 2 is given by

where and are the velocity of 1 and 2 before collision

thus

By energy conservation on second ball we get

Kinetic energy=Potential Energy

thus

weather forecasts are done by collecting data about the current state of the atmosphere mainly the temperature, humidity and wind and using meteorology, to determine the atmosphere that evolves over time. the h and l mean the high and low pressure. the red strip is a warm front. the blue strip is a cold front. the blue and red strip is a stationary front. the purple strip is a occluded front.

explanation: