Given the equations below,which description best fits the physical situation? $$- 99.6 \mathrm {~m} = \left( - 40.0 \frac { \mathrm { m } } { \mathrm { s } } \right) ( 2.00 \mathrm {~s} ) - \frac { 1 } { 2 } \left( 9.80 \frac { \mathrm { m } } { \mathrm { s } ^ { 2 } } \right) ( 2.00 \mathrm {~s} ) ^ { 2 }$$
A)A projectile's displacement two seconds after being fired downward with a speed of 30.0 m/s.
B)A projectile's displacement two seconds after being fired downward with a speed of 40.0 m/s.
C)A projectile's displacement two seconds after being fired downward with a speed of 50.0 m/s.
D)A projectile's displacement two seconds after being fired downward with a speed of 60.0 m/s.
E)A projectile's displacement two seconds after being fired downward with a speed of 80.0 m/s.

Question

Quizplus · Accepted Answer

The equation is a projectile's displacement equation, which is:$$d = vt - \frac{1}{2}gt^2$$where:* d is the displacement* v is the initial velocity* g is the acceleration due to gravity* t is the timeIn this case, the initial velocity is -40.0 m/s (downward), the acceleration due to gravity is -9.80 m/s^2 (downward), and the time is 2.00 s. Plugging these values into the equation, we get:$$d = (-40.0 \mathrm{~m/s})(2.00 \mathrm{~s}) - \frac{1}{2}(-9.80 \mathrm{~m/s^2})(2.00 \mathrm{~s})^2 = -99.6 \mathrm{~m}$$Therefore, the projectile's displacement two seconds after being fired downward with a speed of 40.0 m/s is -99.6 m.

Given the Equations Below,which Description Best Fits the Physical Situation