Physics 201 Test Two

The truck is accelerating at a rate of 2 +1.50 m / s . The mass of the of the crate is 120-kg and it does not slip. The magnitude of the displacement is 65 m. What is the total work done on the crate by all of the forces acting on it?

1.2x10^4J - f=ma and W=(Fcostheta)(d)

A 4.00 kg block is pulled on a frictionless surface a distance d=7.10 m by a constant force F=16.0 N directed at an angle theta = 23.0 deg above the horizontal (see figure). What is the work done by this force

104.58J - f = ma and W=(Fcostheta)(d)

Rain comes down with a velocity of −15 m/s and hits the roof of a car. The mass of rain per second that strikes the roof of the car is 0.060 kg/s. Assuming that rain comes to rest upon striking the car, find the average force exerted by the rain on the roof.

F=-(m/deltat)*v0 F=-0.60kg/s)(-15m/s)

A particle moves in a straight line, parallel to the x axis, from xi to xf. It is acted upon by a force that is also parallel to the x axis and is given by

a). Work done by force - bln(xf/xi) b). -6Nm(5.0m/2.0m)

A box m = 50 kg is being pulled by a constant force F = 100 N at an angle of θ = 60 degrees. The initial speed of the box is zero.

a. Fcostheta(s) - work b. Wnc = 1/2mvf^2 - final velocity

How much power must an automobile engine expend to move a 1200-kg car up a 30 degree at 90 km/h? Assume that 25% of this power is dissipated overcoming air resistance and friction.

196KW - .75P=mgvsintheta

Find the work done if the force is 45.0-N, the angle is 50.0 degrees, and the displacement is 75.0 m

2170J - (Fcos90)s

A motorcyclist is trying to leap across the canyon by driving horizontally off a cliff 38.0 m/s. Ignoring air resistance, find the speed with which the cycle strikes the ground on the other side.

46.2 m/s - vf = sqrt(2(g)(h0-hf)+v0^2)

The gymnast leaves the trampoline at an initial height of 1.20 m and reaches a maximum height of 4.80 m before falling back down. What was the initial speed of the gymnast?

8.4m/s - v0 = sqrt(-2g(h0-hf)

The mass of the space probe is 474-kg and its initial velocity is 275 m/s. If the 56.0-mN force acts on the probe through a displacement of 9 2.42 10 m, ´ what is its final speed?

805 m/s - SumofForces*costheta times s = 1/2mvf^2-1/2mvi^2

The mass of Earth is 5.97×1024kg and the mass of Moon is 7.36×1022kg. The distance between Earth and Moon is 3.82×108m. Determine how far the center of mass of the Earth-moon system is from the center of Earth. Ignore the other objects in the solar system.

=me*re+mm*rm/me+mm

Suppose a 3800 kg space probe expels 3600 kg of its mass at a constant rate with an exhaust speed of 1.0 × 103 m/s. What is the change of the speed of the space probe if the gravity is negligible?

Vinc = Vc*ln(mi/mf)

Two fireworks problem formula

Wnc = mg(hf-h0)+1/2mvf^2

A spacecraft is moving in gravity-free space along a straight path when its pilot decides to accelerate forward. He turns on the thrusters, and burned fuel is ejected at a constant rate of 2.0×102kg/s, at a speed (relative to the rocket) of 2.5×102m/s. The initial mass of the spacecraft and its unburned fuel is 2.0×104kg, and the thrusters are on for 30 s. a) What is the thrust (the force applied to the rocket by the ejected fuel) on the spacecraft? b) What is the spacecraft's acceleration as a function of time? c) What are the spacecraft's accelerations at t= 0, 15, 30, and 35 s?

a.) F=-v(dm/dt) = -(2.5*10^2m/s)(2.0*10^2kg/s) =5*10^4 b) a(t) = F/M-(dmg/dt)(t) c). Plug in each time for t

A hockey puck has a velocity of v = 3i + 2j. Another puck with identical mass is at rest at the origin. The two pucks collide. After the collision it is observed that the second puck has a velocity of vf = 1.0j.

a.) m1v1fx+m2v2fx=m1v1x+m2v2x v1fx=3m/s b.)m1v1fy+m2v2fy=m1v1y+m2v2y v1fy=viy-v2fy =2.0m/s-1.0m/s =1.0m/s c.) arctan(1/3)

A stationary soccer ball of mass m = 0.5 kg is kicked with a constant force of F = 10 N. The player's foot is in contact with the ball for t = 0.10 s. a) Write an expression for the speed of the ball, vi , as it leaves the player's foot. b) What is the velocity of the ball right after contact with the foot of the player? c) If the ball left the player's foot at an angle θ = 30° relative to the horizontal, how high h did it go in meters?

a.) vi = F*t/m c.) vy^2-voy^2=2ay y=(-visintheta)^2/-2*9.8

Three beads are placed on the vertices of an equilateral triangle of side d = 2 cm. The first bead of mass m1 = 100 g is placed on the top vertex. The second bead of mass m2 = 50 g is placed on the left vertex. The third bead of mass m3 = 75 g is placed on the right vertex. a) Write a symbolic equation for the horizontal component of the center of mass relative to the left vertex of the triangle. b) Find the horizontal component of the center of mass relative to the left vertex, in centimeters. c) Write a symbolic equation for the vertical component of the center of mass relative to the base of the triangle. d) Find the vertical component of the center of mass relative to the base of the triangle, in centimeters.

a.)(m1*d/2)+(m3*d/2)/m1+m2+m3 b.) (m1*.8666d)/m1+m2+m3

A block of mass m is initially at rest at the top of an inclined plane, which has a height of 6 m and makes an angle of θ = 30° with respect to the horizontal. After being released, it is observed to be traveling at v = 0.2 m/s a distance d after the end of the inclined plane. The coefficient of kinetic friction between the block and the plane is μp = 0.1, and the coefficient of friction on the horizontal surface is μr = 0.2. a) What is the speed of the block, in meters per second, just after it leaves the inclined plane? b) Find the distance, d, in meters.

a.)vi = sqrt(2(9.8)(sintheta)-ukcostheta))*h/sintheta b.) d =(v^2-vo^2)/2a

A certain carbon monoxide molecule consists of a carbon atom of mass mc = 12 u and an oxygen atom of mass mo = 18 u that are separated by a distance of d = 120 pm, where "u" is an atomic unit of mass. What is the center of mass of carbon monoxide in units of pm.

m1do + m2d/m1+m2

A 60.0 kg skier with an initial speed of 20 m/s coasts up a 2.50 m high rise as shown in the figure. Find her final speed right at the top, in meters per second, given that the coefficient of friction between her skis and the snow is 0.4.

sqrt(v0^2-2gh(1+ukcottheta))

The mass of the block of wood is 2.50-kg and the mass of the bullet is 0.0100-kg. The block swings to a maximum height of 0.650 m above the initial position. Find the initial speed of the bullet.

v0=(m1+m2)vf/m1 vf=sqrt(2ghf) 896m/s

A student produces a power of P = 0.8 kW while pushing a block of mass m = 100 kg on an inclined surface making an angle of θ = 30 degrees with respect to the horizontal. The coefficient of kinetic friction between the block and the incline is μk = 0.3. Assume a.) What is the force applied by the student? b) What is the maximum constant speed, vm in m/s?

v=Power/mgsintheta +ukmgcostheta F= mgsintheta+ukmgcostheta

Starting from rest, two skaters push off against each other on ice where friction is negligible. One is a 54-kg woman and one is a 88-kg man. The woman moves away with a speed of +2.5 m/s. Find the recoil velocity of the man.

vf2= -(m1*vf1)/m2

A small car of mass 1200kg traveling east at 60km/hr collides at an intersection with a truck of mass 3000kg that is traveling due north at 40km/hr. The two vehicles are locked together. What is the velocity of the combined wreckage?

vw_x=(mc/mc+mt)*vc vw_y=(mt/mc+mt)*vt