chapter 9 physics

why magnitude impulse will give 2 kg object a momentum change of magnitude +50 kg&m/s

+50 N *s

a rifle of mass M is initially at rest but free to recoil. it fires a bullet of mass m and velocity v. after firing the velocity of the rifle is

-mv/M

4 N puck is traveling at 3 m/s. it strikes a 8 N puck which is stationary. the two pucks stick tighter. their common final speed is

1 m/s

for a completely inelastic two body collision the kinetic energy retained by the object is the same as

1/2Mvcom^2, where M is the total mass and com is the velocity of the center of mass

.2 kg ball is dropped from the window of a building. it strikes the sidewalk below at 30 m/s and rebounds up at 20 m/s. th impulse on the ball during the collision is

10 N* s upward

bullets from 2 revolvers are fired with the same velocity. the bullet from gun 1 is 2x as heave as the bullet from gun 2. gun 1 weighs 3x as much as gun 2. the ratio fo the momentum imparted to gun 1 to that imparted to gun 2 is

2:1

640 N hunter gets a rope around a 3200 N polar bear. they are stationary 20 m apart on frictionless level ice. when the hunter pulls the polar bear to him the polar bear will move

3.3 m

a 1 kg ball moving at 2 m/s perpendicular to a wall rebounds from the wall at 1.5 m/s. the change in the momentum of the ball is

3.5N S away from the wall

two bodies A and B have equal kinetic energies. the mass of A is 9x that of B. the rain of the momentum of A to that of B is

3:1

75 kg man is riding in 30 kg cart at 2m/s. he jumps off such a way as to lang on the ground with no horizontal velocity.the resulting change in speed of the cart is

5 m/s

2.5 kg stone is released form rest and falls toward earth. after 4s the magnitude of its momentum is

98 kg * m/s

momentum may be expressed in

N*s

for 2 body collision involving objects with different masses, a frame of reference which has the same velocity relative to the laboratory as does the center of mass of the two objects is

a frame for which the total momentum of the two objects is zero

if the total momentum of a system is changing

a net external force must be acting on the system

the momentum of an object at a given instant is independent of its

acceleration

10 kg block of ice is at rest on frictionless horizontal surface. 1N force is applied in easterly direction for 1 s. during this time interval the block

acquires a momentum of 1 kg*m/s

the center of mass of a uniform disk fo radius R is located

at the center

the center of mass of the system consisting of earth the sun and the planet mars is

closer to the sun than to either of the other bodies

force

equals the time rate of change momentum

object A strikes the stationary object B head-on In an elastic collision, the mass of A is fixed, you may choose mass of B appropriately

for B ot have greatest recoil kinetic energy, choose mb=ma

the thrust of a. rocket is

force fo the exiting fuel gases on the rocket

two objects P and Q, have the same momentum. Q has more kinetic energy that P if it

is moving faster than P

a man sits in the back of a canoe in still water. he then moves to the front of the canoe and sits there. afterwards the canoe

is rearward of its original position and not moving

a projectile in flight explodes into several fragments, the total momentum of the fragments immediately after this explosion

is the same as the momentum of the projectile and immediately before the explosion

the center of mass of a system of particles remains at he same place if

it is initially at rest and the external forces sum to zero

an elastic collision is one in which

kinetic energy and momentum are both conserved

the physical quantity "impulse" has the same dimensions as that of

momentum

an inelastic collision is one which

momentum is conserved by kinetic energy is not conserved

the center of mass of earths atmosphere is

near the center of earth

the center of mass of a system of particles has a constant velocity if

the external forces acting on particles of the system sum to zero

when you step on the accelerator to increase the speed of your car, the force that accelerates the car is

the force of friction of the road on the tires

when a particle suffers a head-on elastic collision with another particle, initially at rest, the greatest fraction of kinetic energy is transferred if

the incident and target particle have the same mass

the law of conservation of momentum applied to a system of colliding objects only if

the net external impulse is zero

sphere X of mass 2 kg is moving to the right at 10 m/s. sphere Y of mass 4 kg is moving to left at 10 m/s. the two coheres collide head on. the magnitude of the impulse of X on Y is

the same as the magnitude of impulse of Y on X

two bodies of unequal mass, placed at rest on a frictionless surface are acted on by equal horizontal forces for equal times. just after these forces are removed, the body of greater mass will have

the same momentum as the other body

a cart loaded with sand slides forward along a horizontal frictionless track. as the cart moves, sand trickles out at a constant rate through a hole in the back of the cart. the acceleration of the cart is

zero