Question
all please
A constant net force acts on an object. Describe the motion of the object. A) Constant acceleration B) Constant speed C) Constant velocity D) Increasing acceleration When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while travelling in empty space the starship will A) stop immediately. B) slowly slow down and then stop. C) go faster and faster. D) move with constant speed. A net force F acts on a mass m and produces on acceleration a. What acceleration results if a net force 2F acts on mass 4m. A) 0/2 B) 80 C) 40 D) 20 Your bat hits the ball pitched to you with a 1500-N instantaneous force. The ball hits the bat with an instantaneous force, whose magnitude is A) some what less than 1500 N B) somewhat greater than 1500 N C) exactly equal to 1500 N D) essentially zero. Who has a greater weight to mass ratio, a person weighing 400 N or a person weighing 600 N A) the person weighing 400 N B) the person weighting 600 N C) Neither their ratio are the scene. D) The question can't be answered not enough information is given. A block of mass A slides down a frictionless plane inclined at an angle theta with the horizontal the normal reaction force exerted by the plane on the block is [Assuming a fitted coordinate system] A) Mg B) Mg sin theta. C) Mg cos theta. D) zero, since the phone is frictionless. An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and velocity and acceleration vectors. A) Both vectors point in the same direction. B) The vectors point in opposite directions C) The vectors are perpendicular. D) the question is meaningless, since the acceleration zero.
Explanation / Answer
(1)
From the Newton's second law of motion, the net force acting on an object is,
F=ma
the acceleration of the object is constant if the force is constant. Correct option is A.
(2)
to move with a constant speed, no net force is required. so, the correct option is D
(3)
F/F' = ma /m'a'
F/2F= ma /4ma'
a'=a/2 correct option is A
(4)
From Newton's third law, for any action there will be an opposite reaction.
so, the correct option is C
