Answer:
-1.11 m/s²
Explanation:
v = at + v₀
Given v = 20 m/s, v₀ = 120 m/s, and t = 1.5 min = 90 s:
20 m/s = a (90 s) + 120 m/s
a = -1.11 m/s²
Answer:
Yes the ramp can be safely used
Explanation:
Here, we have
Length of longest ramp = 5 ft
Height of wall = 2 ft
Therefore, the sine of the angle adjacent to the ramp which is equal to the angle of elevation is given by;
Where:
The opposite side to angle = 2 ft wall and
Hypotenuse side = Ramp = 5 ft
Therefore,
and θ = sin⁻¹0.4 = 23.55 °
The ramp can be safely used as the angle it is adjacent to is less than the specified 30°.
Answer: initially the packet was ascending up with the balloon.
Taking upward as positive direction;
initial velocity, u = 4.9 m/s
final velocity = v m/s
initial height, h₁ = 245 m
final height, h₂ = 0
a = -9.8 m/s²
time taken = t seconds
s = ut + 0.5at²
⇒ (h₂-h₁) = ut + 0.5at²
⇒ 0-245 = 4.9t + 0.5×(-9.8)×t²
⇒ -245 = 4.9t - 4.9t²
⇒ 4.9t² -4.9t -245 =0
Solving it, we get t = 7.59s
v = u + at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/s
So velocity is 69.48 m/s downward
Explanation:
The hint is "constant speed".
If there is a net force on an object, what occurs to that object? F net = m*a.... It accelerates!
So, if the desk is going at a CONSTANT speed, what does that tell you about the acceleration? There is a change in speed.
Fnet = m*a Since a = 0 Fnet = 0
Fnet = sum of the force... reflect the direction of F as the positive direction. Sum of the forces in the direction of F = 0 0 = F - friction F = friction
So, if F = 800 N, then friction = 800 N in the opposite direction.
When someone lifts a book from the ground, the work you use is positive. By lifting the book, you change it's energy and it's original place The book gains, kinectic energy.
Hope I helped.
