Mechanics | Relativity Answers

In sound waves,is the constructive interference is where compression meets compression or where displacements of particles add up to form resultant displacement greater?But pressure amplitude and displacement amplitude is 90 degrees out of phase.

Find the time taken for a car to travel 98m if it start from rest and accelerate at 4.00 m/s

A spear was thrown at an angle and it stayed in the air for 7 second right before it hit the
ground.
1) What is the peak height of the spear (dy peak)?
2) What is the initial vertical velocity (Vyi)?
3) If the spear landed 230m away from the thrower, what is the initial velocity? (launch Vi)
4) What is the angle that the spear was thrown?
5) When t = 3.5s what is Vx and Vy at that moment?
6) What is dx and dy when t= 3.5s?
7) When t= 4.9s what is Vx and Vy at that moment?
8) What is dx and dy when t= 4.9s?

A block of mass 20.0 kg slides from rest down a slope 2.00 meters long which is inclined at 37.6° to the horizontal. The coefficient of kinetic friction is 0.343. What is the speed of the block at the bottom of the slope?
Select one:
a. 4.33 m/sec
b. 5.57 m/sec
c. 2.86 m/sec
d. 3.14 m/sec
e. 3.64 m/sec

A box of mass 41.9 kg is moving across a level floor at a speed of 3.53 m/sec. A kinetic friction force of 104.4 N is acting on the box directed against its motion. How far must the box move for the force of friction to bring it to rest?
Select one:
a. 4.07 m
b. 2.13 m
c. 17.3 m
d. 2.50 m
e. 3.31 m

A hiker throws a stone directly downward from a cliff with a speed of 10.0 m/sec. The stone travels 35.4 meters downward before hitting a rotten log. What is the speed of the stone just as it reaches the log? Assume there is negligible friction or drag force.
Select one:
a. 28.2 m/sec
b. 29.9 m/sec
c. 24.4 m/sec
d. 26.3 m/sec
e. 33.3 m/sec

A box of mass 22.3 kg is pushed 7.32 meters uphill on an inclined plane sloped at 17.6° to the horizontal. What is the change in its potential energy?
Select one:
a. -803 J
b. 1525 J
c. 484 J
d. 803 J
e. 2.21 J

A Ford Focus of weight 9800 N is moving at 25.0 m/sec along a level road surface. The driver applies the brakes and it slows to 18.0 m/sec over a distance of 70.0 meters. How much work did the braking force do on the car? You may assume that friction and drag are negligible and that weight and normal force cancel out, making the braking force the net force on the car.
Select one:
a. -150,500 J
b. -2150 J
c. -162,000 J
d. -475,000 J
e. -312,500 J

A softball is tossed into the air at an angle of 56.9 degrees with the vertical (that would be 33.1 degrees with the horizontal). The initial velocity is 19.5 m/s. What is the maximum height of the softball?

You throw a ball downward from a window at a speed of 4.50 m/s (about 10.1 mph). What is the velocity of the ball as it hits the sidewalk 3.80 m (about 12 feet) below?


What would the impact velocity have been if you had thrown the ball upward with a speed of 4.50 m/s?