Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.) A) The speed of the object is constant but its velocity is not constant. B) The acceleration of the object is constant but its object is + g when the object is rising and -g when it is falling. C) The acceleration of the object is zero at its highest point. D) The speed of the object is zero at its highest point. E) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward

Object often experience acceleration when in motion. The statement that is  true is that The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

Two-dimensional projectiles often shows constant downward acceleration due to gravity. Always note  Nothing can accelerates a projectile horizontally, so horizontal acceleration is simply zero.

A projectile in motion is said too be the same with the same horizontal velocity throughout its flight. This is because there is no force exists in the horizontal direction, but its velocity will be altered in the vertical direction as a result of the force of gravity.

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The correct answers are

The following statements are true about an object in two-dimensional projectile motion with no air resistance

D) The speed of the object is zero at its highest point.

E) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward

Explanation:

A) The speed of the object is constant but its velocity is not constant.

False the vertical velocity increases on descent

B) The acceleration of the object is constant but its object is + g when the object is rising and -g when it is falling.

False, the acceleration is -g when the object is rising

C) The acceleration of the object is zero at its highest point.

False, the acceleration is constant in magnitude throughout the motion

D) The speed of the object is zero at its highest point.

True, the direction of motion changes at the highest point from hence the body comes to rest and the speed is zero

E) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward

True, the horizontal acceleration has associated force during motion but the vertical acceleration is due to gravity which is constant downwards

There was no intial y-momentum so the net final y-momentum must also be 0. they can have final velocities in the y-direction

The inference is supported by evidence in the graph is this is an exothermic reaction where the total release of energy equals a + c.