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A car moves along an x axis through a distance of 900 m, starting at rest (at x = 0) and ending at rest (at x = 900 m). Through the first 1/4 of that distance, its acceleration is +6.25 m/s2. Through the next 3/4 of that distance, its acceleration is -2.08 m/s2. What are (a) its travel time through the 900 m and (b) its maximum speed?
<span>Solve for the time at the 1/4 mark. That's 225 m. How? d = (1/2)at^2 ( initial velocity zero). Thus 225 = (1/2) 6.25 t^2. t^2 = ( 225 * 2 ) / 6.25. t = 8.5 sec. </span>
<span>At the other end t^2 = (675 * 2) / 2.08 -- we reversed the sign and ran time backwards. t = 25.5 sec. </span>
<span>So total time is 8.5 + 25.5 or 34 sec. </span>
<span>Since zero initial velocity: v^2 = 2 a d. Here, v^2 = 2 * 6.25 * 225. v = 53 m/s. That's the fastest speed since braking then occurs.</span>
Answer:
D potential energy at the top of the stairs, kinetic energy as she walks down
Explanation:
The potential energy of a body is the energy due to the position of the body.
At the top of the stair case, the student is at a significant height.
Kinetic energy is the energy due to the motion of the body.
As the student descends, the potential energy is changed to kinetic energy.
To find the potential energy;
P.E = mgH
m is the mass
g is the acceleration due to gravity
H is the height of the body
To find the kinetic energy;
K.E = 
m v²
m is the mass
v is the velocity
Yes. Displacement is a vector, as opposed to distance, which is a scalar. Since displacement is a vector quantity, the negative sign represents direction. As with velocity and acceleration, it just comes down to how you define your coordinate system
Answer:
F=
Explanation:
The magnitude of force required to pull the lid off the box by air pressure.
We know that Pressure, P= Force(F)/Area(A)
Force, F= P×A
Given: A=
P=
.
Therefore, F=
.
F=
