Answer:
B) A stack of books is carried at waist level across a room
Explanation:
Work is defined as:
where
F is the force applied
d is the displacement of the object
is the angle between the direction of the force and of the displacement
From the formula, we see that the work done is zero when the force and the displacement are perpendicular to each other. Let's now analyze each situation:
A) A bookcase is slid across carpeting. --> work is done, because the force that pushes the bookcase is in the same direction of the displacement
B) A stack of books is carried at waist level across a room. --> no work is done, because the force to carry the book is vertical, while the displacement of the books is horizontal
C) A chair is lifted vertically with respect to the floor. --> work is done, because the force that lifts the chair is vertical, and the displacement is vertical as well
D) A table is dropped onto the ground. --> work is done, because the force of gravity (that makes the table falling down) is vertical and the displacement of the table is also vertical.
It’s gonna have to b since it’s decreasing
Answer:
Explanation:
Using kinematics equations:
Use due to condition of distance traveled.
Solving second equation for time, there are two solutions. t=0 and
Use the expression in the first equation to have
Using trigonometric identities, you have the answer of the distance.
By doing the ratio for two different angles, you have the second answer. Due to sine function properties, the distances can be the same to complementary angles. Example, for 20° and 70°, the distance is the same.
Answer:
& -y direction
& +y direction
Explanation:
From the question we are told that:
Speed of electron +x direction
Earths magnetic field +z direction
a)
Generally the equation for magnetic force is mathematically given by
where
Magnitude & Direction
-y direction
b)
Generally the equation for magnitude and direction of the magnetic force on an electron. is mathematically given by
Magnitude & Direction
& +y direction
Answer:
Momentum P is 840000kgm/s or 8.4 × 10^6
Explanation:
Data :
Mass = 21000 kg
Velocity = 400 m/s
So momentum is given as
P = mv
P = 21000×400
P = 8400000 kgm/s
P = 8.4 × 10^6