A ball is kicked from the top of a building with a velocity of 50 m/s and lands 165 m away from the base of the building.
1 answer:
Answer:
3.1 s
Explanation:
we can assume that this motion has a horizontal projectile motion.
projectile motion happens when an object is subjected to only gravity. Gravity acts to influence the vertical motion of the projectile, it makes a vertical acceleration.
The horizontal motion of the projectile is the result of the constant velocity of the object.We assume no acceleration in the horizontal direction.
applying motion equations
where
s - distance
u - initial velocity
a-acceleration
t - time
s = ut + (1/2)at²
→ 165 = 50t + 0 (as no acceleration is in horizontal direction)
t = 3.1 s
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(a) The electrons move horizontally from west to east, while the magnetic field is directed downward, toward the surface. We can determine the direction of the force on the electron by using the right-hand rule:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.
b) From the kinetic energy of the electrons, we can find their velocity by using
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
And finally we can calculate the centripetal acceleration, given by:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.
b) From the kinetic energy of the electrons, we can find their velocity by using
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
And finally we can calculate the centripetal acceleration, given by: