【单选题】On an airless planet, an astronaut drops a hammer from a height of 15 m. The hammer hits the ground in 1 s. What is the acceleration due to the gravity on this planet?
【单选题】A 20 - kg object is resting at the top of a table 1.6 m above ground level. The object is then picked up and moved to a height of 8.7 m above ground level. What is the change in the gravitational pote...
【单选题】A 1.0kg ball moving at 10m/s strikes a wall and bounces back. Thecollision is perfectly elastic. What is the ball’s momentum after the collision?(Assume a frictionless suce.)