However, the statement is true provided that the vertical component of the launch velocity for the two motions are the same.
You also require that both motions end at the same level and that the air resistance etc can be disregarded. The first of these may not always be valid in school exercises, the second is usually implicit.
yes, i am a scientist and i have tried this in class
Velocity is the time rate of change of displacement of an object. Velocity is the distance travelled in unit time in a stated direction. It is a vector quantity since it gives us both magnitude and direction.
45 degrees to the horizontal will give the maximum flight time for a projectile. If a projectile was fired at 90 degrees to the horizontal, (straight upwards) the projectile will go straight upwards (ignoring the shape, form and aerodynamic properties of the projectile). Likewise if you were to fire a projectile at 0 degrees to the horizontal, the projectile would follow said course, IF gravity was not in effect; a projectile needs some form of vertical velocity to overcome gravity. Hence why 45 degrees will give you the longest distance and consequently flight time.
A projectile will travel on a straight line unless external forces act upon it. Gravity will pull the projectile downward, i.e. affect its vertical velocity component. This is why the projectile will decelerate upwards, reach a maximum elevation, and accelerate back down to earth. The force vector of air resistance points in the opposite direction of motion, slowing the projectile down. For example, If the projectile is going forward and up, air resistance is pushing it backwards (horizontal component) and down (vertical component). Without air resistance, there is no external force acting upon the horizontal velocity component and the projectiles ground speed will stay constant as it gains altitude and falls back down to earth.
When an object is moving upwards, its velocity is directed upwards. If the object is near the Earth or any other planet, then its acceleration is directed downwards, which also means that its upward velocity is decreasing.
In that case, the velocity is zero.
Using the equation: x=vot+(1/2)at2 x: -39.2m (though the object is thrown upwards, its total displacement is just the amount it fell from the tower). vo: initial velocity t: 4 s a: -9.8m/s2 (assuming we're on the earth's surface) -39.2=vo(4 s)+(1/2) (-9.8m/s2)(4 s)2 ((78.4 m - 39.2 m)/ 4 s) = v0 So the initial velocity is 9.8 m/s.
A projectile fired directly upwards has no positive velocity. Its only velocity is attributed to the force of gravity, which is -9.8 meters per second squared.
The velocity of such an object changes all the time. Assuming you throw something directly upwards and there is no wind, it will go upwards, slower and slower, until it reaches its highest point. At that moment, its velocity is zero. Then, still as a result of gravity, it will move downward, faster and faster.
when a ball is thrown upwards velocity increases but acceleration decreases hence making it anti parallel to each other
In the act of "throwing", the thrower imparts an upward velocity to the object, by temporarily applying an upward force to it that's greater than the downward force of gravity. During that brief period, the sum of the forces on the object is directed upward, so it accelerates in that direction. After the throwing ends, however, the only force on the object is the force of gravity, directed downward, so its acceleration is downward. That means that the upward velocity becomes smaller and smaller, until it's zero at the peak of the arc, and the velocity then becomes downward as the object begins to fall from its peak..
Its velocity decreases because gravity is pulling on it as it goes up. Its acceleration increases.
A projectile, launched by an initial force, such as exploding gunpowder in the barrel of a gun, travels in a straight line unless it is acted upon by another force. A projectile launched into the air from the earth's surface, is subject to the acceleration of gravity, which bends it's trajectory into a parabolic arc back to earth.