Answer
given,
mass of the piano = 170 kg
angle of the inclination = 20°
moves with constant velocity hence acceleration = 0 m/s²
neglecting friction
so, force required to pull the piano
F = m g sin θ
F = 170 × 9.81 × sin 20°
F = 570.39 N
so, force required by the man to push the piano is F = 570.39 N
Answer:
An object which moves in the positive direction has a positive velocity. If the object is slowing down then its acceleration vector is directed in the opposite direction as its motion (in this case, a negative acceleration).
Explanation:
First, calculate how long the ball is in midair. This will depend only on the vertical displacement; once the ball hits the ground, projectile motion is over. Since the ball is thrown horizontally, it originally has no vertical speed.
t = time vi = initial vertical speed = 0m/s g = gravity = -9.8m/s^2 y = vertical displacement = -45m
y = .5gt^2 [Basically, in this equation we see how long it takes the ball to fall 45m] -45m = .5 (-9.8m/s^2) * t^2 t = 3.03 s
Now we know that the ball is midair for 3.03s. Since horizontal speed is constant we can simply use:
x = horizontal displacement v = horizontal speed = 25m/s t = time = 3.03s
x = v*t x = 25m/s * 3.03s = 75.76 m Thus, the ball goes about 75 or 76 m from the base of the cliff.
I think number 1 is incorrect I believe that answer is D. Number 6 I believe would be B. The rest seem to be correct.
