)
5
-5
1 2 3
4
5
Other than at t = 0, when is the velocity of
the object equal to zero?
1. 5.0 s
2. 4.0 s
3. 3.5 s
4. At no other time on this graph. correct
5. During the interval from 1.0 s to 3.0 s.
Explanation:
Since vt =
Z t
0
a dt, vt
is the area between
the acceleration curve and the t axis during
the time period from 0 to t. If the area is above
the horizontal axis, it is positive; otherwise, it
is negative. In order for the velocity to be zero
at any given time t, there would have to be
equal amounts of positive and negative area
between 0 and t. According to the graph, this
condition is never satisfied.
005 (part 1 of 1) 0 points
Identify all of those graphs that represent motion
at constant speed (note the axes carefully).
a) t
x
b) t
v
c) t
a
d) t
v
e) t
a
The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.
Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg
F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)
F = 83 N
Answer:
45 m / s North is a valid vector reading for an object.
Explanation:
Then velocity will be defined by x km / hr North. And, magnitude of velocity defines the speed of the body. Although this tells the speed, but there is no description for the direction, so it's not a vector reading
Magnitude of acceleration = (change in speed) / (time for the change).
Change in speed = (27 - 0) = 27 m/s
Time for the change = 10 s
Magnitude of acceleration = (27 m/s) / (10 s) = 2.7 m/s² .
