A block of mass m = 3.7 kg slides from left to right across a frictionless surface withra speed v; - 7.4 m/s. It collides in a perfectly elastic collision with a second block of mass M that is at rest. After the collision, the 3.7-kg block reverses direction, and its new speed is vf 2.2 m/s. What is M?

8.9 kg
6.8 kg
5.2 kg
7.5 kg

The current in a hair dryer measures 11 amps. the resistance of the hair dryer is 12 ohms. what is the voltage?unit:

An architect plans to use solar energy to heat the next house he designs. what principle of absorption and infrared energy can be applied to the design of the new house? how could she apply to those principals?

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.