A 1.35kg object is initially at rest. It is then launched at 1.15m/s. If the launch took 0.02s to happen, what force was needed to cause this change? (Please help!!!)

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s

Which changes would result in a decrease in the gravitational force btween two objects? check all that apply

What is friction? how does it affect the motion of an object?