Answer:
Explanation:
The electric field produced by a single point charge is given by:
where
k is the Coulomb's constant
q is the charge
r is the distance from the charge
In this problem, we have
E = 1.0 N/C (magnitude of the electric field)
r = 1.0 m (distance from the charge)
Solving the equation for q, we find the charge:
Answer:
<em>Explanation below</em>
Explanation:
<u>Speed vs Velocity </u>
These are two similar physical concepts. They only differ in the fact that the velocity is vectorial, i.e. having magnitude and direction, and the speed is scalar, just the magnitude regardless of the direction. They are strongly related to the concepts of displacement and distance, which are the vectorial and scalar versions of the space traveled by a moving object. The velocity can be computed as
Where is the position vector and t is the time. The speed is
To compute , we only need to know the initial and final positions and subtract them. To compute d, we need to add all the distances traveled by the object, regardless of their directions.
Maggie walks to a friend's house, located 1500 meters from her place. The initial position is 0 and the final position is 1500 m. The displacement is
and the velocity is
Now, we know Maggie had to make three different turns of direction to finally get there. This means her distance is more than 1500 m. Let's say she walked 500 m in all the turns, then the distance is
If she took the same time to reach her destiny, she would have to run faster, because her average speed is
Answer:
Approximately (assuming that
.)
Explanation:
The question provided very little information about this motion. Therefore, replace these quantities with letters. These unknown quantities should not appear in the conclusion if this question is actually solvable.
This answer will approach this question in two steps:
For simplicity, let represent the tangential acceleration (
) of this car.
The question gave no information about the distance that the car has travelled before it skidded. However, information about the angular displacement is indeed available: the car travelled (without skidding) one-quarter of a circle, which corresponds to or
radians.
The angular acceleration of this car can be found as . (
is the tangential acceleration of the car, and
is the radius of this circular track.)
Consider the SUVAT equation that relates initial and final (tangential) velocity ( and
) to (tangential) acceleration
and displacement
:
.
The idea is to solve for the final angular velocity using the angular analogy of that equation:
.
In this equation, represents angular displacement. For this motion in particular:
Solve this equation for in terms of
and
:
.
Let represent the mass of this car. The centripetal force at this moment would be:
.
Since the track is flat (not banked,) the only force on the car in the horizontal direction would be the static friction between the tires and the track. Also, the size of the normal force on the car should be equal to its weight, .
Note that even if the size of the normal force does not change, the size of the static friction between the surfaces can vary. However, when the car is just about to skid, the centripetal force at that very moment should be equal to the maximum static friction between these surfaces. It is the largest-possible static friction that depends on the coefficient of static friction.
Let denote the coefficient of static friction. The size of the largest-possible static friction between the car and the track would be:
.
The size of this force should be equal to that of the centripetal force when the car is about to skid:
.
Solve this equation for :
.
Indeed, the expression for does not include any unknown letter. Let
. Evaluate this expression for
:
.
(Three significant figures.)