Q. A football is kicked at ground level with the speed of 20.10 m/s at an angle of 36.40° to the horizontal. How much later does it hit ground?

a) Tubby is in an accelerating (non-inertial) reference frame, and sees an object that is stationary. What result can he draw about net force acting on an object?

The net force on the object is not zero in Tubby's frame, but there is an inertial frame in which net force is zero

The net force on the object is zero in Tubby's frame, but there is an inertial frame in which net force is not zero

The net force on the object cannot be zero

Nothing can be concluded about the net force on object.

The net force on the object might be zero.

The net force on the object has to be zero

b) Tonga is in an inertial reference frame. If two forces of equal magnitude act on an object, what will she see?

The object might be moving at constant speed, but cannot be stationary or accelerating

The object might be moving at constant speed and may be stationary, but cannot be accelerating

The object can be accelerating, may be moving at constant speed, and may be stationary

The object could be accelerating, but cannot be moving at constant speed or stationary

The object might be accelerating or may be stationary, but cannot be moving at constant speed

The object can be accelerating or moving at constant speed, but cannot be stationary