How far should an object be held from a concave mirror of focal length 40cm so as to obtain a real image twice the size of the object? 1. 10cm
2. 20cm
3. 30cm
4. 60cm

Abatter hits the baseball a with an initial velocity of v0 = 110 ft/sec directly toward fielder b at an angle of 23° to the horizontal; the initial position of the ball is 2.2 ft above ground level. fielder b requires 0.44 sec to judge where the ball should be caught and begins moving to that position with constant speed. because of great experience, fielder b chooses his running speed so that he arrives at the “catch position” simultaneously with the baseball. the catch position is the field location at which the ball altitude is 8.4 ft. determine the velocity of the ball relative to the fielder at the instant the catch is made.

If a textbook weighs 37.2 n on venus, and the book has a mass of 4.4 kg, what is the strength of gravity on venus? 8.9 m/s28.9 m/si don't have enough information,9.8 m/s2

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •