6. factoring in the effect of friction, what must be true about the work output?
1. it must be less than 60 j.
2. it equals 60 j.
3. it must be greater than 60 j.

Achild throws a ball with an initial speed of 8.00 m/s at an angle of 40.0° above the horizontal. the ball leaves her hand 1.00 m above the ground. how long is the ball in flight before it hits the ground?

If 21.2 kcals of energy is released by this reaction, how many kj does the reaction release? (1 cal 4.184 j)

Which best represents the law of conservation of mass ?