The directions of the velocity and acceleration of an object which is thrown straight upward and then falls back down (ignore the effects of air resistance) have the following characteristics:
A. the velocity and acceleration are always directed downward
B. the velocity is always upward
but the acceleration changes direction
C. the velocity is always upward and the acceleration is always downward
D. the velocity changes direction but theacceleration always stays the same
D. the velocity changes direction (blue arrows) but the acceleration
always stays the same (green arrows), see figure 3.10 in text.
You might also like to view...
Besides Earth, which terrestrial planet also has seasons?
A. Mercury B. Mars C. Venus D. Seasons are unique to Earth.
Discuss whether any work is being done by each of the following agents and, if so, whether the work is positive or negative
(i) a chicken scratching on the ground (ii) a person studying physics (iii) a crane lifting a bucket of concrete (iv) the gravitational force on the bucket in (iii) (v) the leg muscles of a person in the act of sitting down
1.All of them do work. Positive work is done in cases (i), (ii), and (iii) and negative work is done in cases (iv) and (v). 2.No work is done in case (ii). Positive work is done in cases (i) and (iii) and negative work is done in cases (iv) and (v). 3.No work is done in cases (i) and (ii). Positive work is done in case (iii) and negative work is done in cases (iv) and (v). 4.No work is done in cases (i) and (ii). Positive work is done in cases (iii) and (v) and negative work is done in case (iv).Of these properties of waves, which one is independent of the others?
A. amplitude B. speed C. frequency D. wavelength
How do we learn about the conditions at the center of our own galaxy, the Milky Way?
A) The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there. B) We must look at the centers of other (external) galaxies and assume that they are similar to the Milky Way. C) While we cannot see the galactic center with visible or ultraviolet light, radio and X-rays from the center can be detected and used to determine the conditions there. D) High-resolution photographs obtained by the Hubble Space Telescope have revealed the galactic center using visible light.