JAMB UTME Kinematics — practice questions — page 2

1. Free fall is defined as falling without air resistance or friction. 2. The only influence left is gravity, so the acceleration is constant at 9.80 m/s^2 on Earth. 3. Constant acceleration means the velocity keeps changing, so a constant velocity is wrong. 4. Free fall applies to upward motion as well, so it is not limited to objects thrown down. _Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.7 Falling Objects_

1. Gravity is a general characteristic and is not unique to Earth. 2. On the Moon the acceleration due to gravity is only 1.67 m/s^2. 3. That is far smaller than the 9.80 m/s^2 measured on Earth. 4. A hammer and a feather still fall together on the Moon, only more slowly. _Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.7 Falling Objects_

1. Identify the knowns: the initial velocity is -13.0 m/s, the displacement is -5.10 m and the acceleration is -9.80 m/s^2. 2. All three are negative because upward has been taken as the positive direction. 3. Use the relation that links velocity, acceleration and displacement without time. 4. Substitute the values: (-13.0 m/s)^2 + 2 x (-9.80 m/s^2) x (-5.10 m). 5. This gives 169 m^2/s^2 + 99.96 m^2/s^2 = 268.96 m^2/s^2. 6. Take the square root, which yields plus or minus 16.4 m/s. 7. The rock is still heading down, so the negative root is chosen and the velocity is -16.4 m/s. 8. Simply adding the two speeds gives 22.6 m/s, which is not how the relation works. _Source: OpenStax College Physics (CC BY 4.0), Ch 2 "Kinematics", section 2.7 Falling Objects_