Kinematics and Newtons laws
t=0.88s
ymax=0.95m
The work required for a 75 kg firefighter to climb a flight of stairs that is 20.0m high.
W = 1.47x104 J
The force exerted on a rocket when the propelling gases are being expelled at a rate of 1300 kg/s with a speed of 4.5x104 m/s.
The blades in a blender rotate at a rate of 6500 rpm. When the motor is turned off during operation, the blades slow to a rest in 4.0s. What is the angular accelerations?
alpha = -170 rads/s/s
Three forces are applied to a tree sapling as shown (nick will draw). If Fa =385N and Fb = 475N find the magnitude and direction of Fc
Fc = 528 N at theta = 120o
The position and acceleration as a function of time, given that a particle has a velocity of
V = (-2.0i +3.5tj)m/s and position r = (1.5i - 3.1j) m at t = 0
a =3.5j m/s/s
r = (1.5 - 2.0t)m i + (-3.1 + 1.75t2)m j
The total work of a child pulling a wagon, first with a 22N horizontal force for 9.0m. Then a wheel dips into the grass, and he pulls with a 38N force at a 12o angle for 5.0m. Then the wheel makes it back on the sidewalk for the last 13m, the kids pulls with a 22N horizontal force.
w = 670J
the mass of a boxcar, if another boxcar (mass = 7700 kg) traveling at 18m/s strikes it and the two stick together.
mb = 2.0 x 104 kg
The angular acceleration and the number of revolutions when an engine slows down from 3500rpm to 1200 rpm in 2.5s.
alpha = -96 rad/s/s
theta = 98 revs
The two tree (drawn by nick) are 6.6 m apart. A back-packer is trying to lift his pack out of the reach of bears. Calculate the magnitude of force F that he must exert downward to hold a 19kg backpack so that the rope sags at its midpoint by 1.5m
The time it takes for a bar of slope (mass = 150g) to slide down a 3.0m ramp with incline of 8.5o.
t = 8.5s
A) the speed at the the highest point
B)the highest point
of a .40 kg ball thrown with speed 8.5m/s upwards at an angle of 36o
speed = 6.9 m/s
highest point = 1.3m
The velocity of mb if,
A mass ma = 2.0kg, moving with velocity
va=(4.0i + 5.0j -2.0k) collides with mb = 3.0kg which is initially at rest. After the collision ma is observed traveling at va' = (-2.0i + 3.0k) m/s.
v2' = (4.0i + 3.3j - 3.3k)m/s
A wheel of diamter 27.0cm is constrained to rotate in the xy plane about the z axis. A force F = (-31.0i + 43.4j) N acts at a point on the edge of the wheel that lies exactly on the x axis at a particular instant. What is the torque about the rotation axis at this instant?
Torque = 5.86 N m, CCW
A large 62 kg board is propped at a 45o angle against the edge of a barn door that is 2.6m wide. How great a horizontal force must a person behind the door exert in order to open it? Assume negligible friction between the door and the board but that the board is firmly set against the ground.
Fpush = 303.8N
The tension in both ropes, of a group of three hikers ascending an inclined icefield at 31.0o. The climbers each weight 75 kg. The last climber slips and pulls the second down, with the first being able to stay upright.
T2 (between last two) = 380N
T1 (between first two) = 760N
The work done by the force of Earths gravity on a space vehicle (mass = 2800kg) that falls vertically from rest at 3300km above Earths surface.
W = 6.0 x 1010J
The velocity of the third piece of a puck (mass = 4m), if the puck is rigged to explode and is placed on a frictionless ice rink. When it bursts the first piece of mass m, travels at velocity vi, and the second piece of mass 2m, travels at velocity 2vj.
v3= (-vi -4vj)
a 1.4 kg grindstone in the shape of a uniform cylinder of radius 0.20 m acquires a rotational rate of 18 rev/s from rest over a 6.0 s interval at constant angular acceleration. Calculate the torque
torque = 53 N m
A tightly stretched "high wire" is 36m long. It sags 2.1 m when a 60.0 kg tightrope walker stands at its center. What is the tension in the wire?
Ft = 2500N
The acceleration of the frictionless system (drawn by nick) in terms of ma, mb, thetaa, thetab.
The launch height of a small mass sliding without friction along the looped track (nick will draw), if it is to remain on the track at all times, even at the top of the loop.
h = 2.5r
the vertical and horizontal component of a pendulum (mass = 3.6kg) attached to a 2.8m long string after it is struck by a bullet (mass = 28g) traveling at 210 m/s
y = .134m
x= .86m
A wheel of mass M has radius R. It is standing vertically on the floor, and we want to exert a horizontal force F at its axle so that it will climb a step against which it rests. The step has height h, where h < R. What is the minimum force needed?
Two identical, uniform beams are symmetrically set up against each other, on a floor with which they have a coefficient of friction mus = 0.40. What is the minimum angle the beams can make with the floor and still not fall.
theta = 51.34o