A baseball outfielder throws a baseball of mass 0.15 kg at a speed of 40 m/s and initial angle of 30°. What is the kinetic energy of the baseball at the highest point of the trajectory?
90 J
You might also like to view...
Two 1.5 m-square and parallel flat plates are 30 cm apart. Plate A1 is maintained at a temperature of 1100 K and A2 at 500 K. The emissivities of the plates are 0.5 and 0.8, respectively. Considering the surroundings black at 0 K and including multiple inter-reflections, determine (a) the net radiant exchange between the plates and (b) the heat input required by surface A1 to maintain its temperature. The outer-facing surfaces of the plates are adiabatic.
GIVEN
? Two square parallel flat plates, 30 cm apart
? Temperature of A1 (T1) = 1100 K
? Temperature of A2 (T2) = 500 K
? Emittances: ?1 = 0.5 ?2 = 0.8
? Surroundings are black at (T3) = 0 K
FIND
Including multiple inter-reflections, determine:
(a) The net radiant exchange (q1–2)
(b) The heat input at surface A1 (q1) required to maintain its temperature
SKETCH
PROPERTIES AND CONSTANTS
When a net horizontal force of 250 N acts on a 50-kg cart that is free to roll on a level surface,
A. the cart accelerates at 12500 m/s2. B. the cart accelerates at 9.8 m/s2. C. the cart accelerates at 5 m/s2. D. the cart accelerates at 0.20 m/s2. E. the cart does not accelerate because it pushes back on the person with a force of 250 N.
During the eighteenth and nineteenth centuries, attempts to precisely measure the astronomical unit relied largely on rare:
A) total solar eclipses. B) transits of the inferior planets across the Sun. C) passages of comets close to the Earth. D) maximum elongations of Venus. E) oppositions of Mars.
A girl and her bicycle have a total mass of 40 kg. At the top of the hill her speed is 5.0 m/s. The hill is 10 m high and 100 m long. If the force of friction as she rides down the hill is 24 N, what is her speed at the bottom?
a. 5.0 m/s c. 11 m/s b. 10 m/s d. She stops before she reaches the bottom.