solutions
Physics Exam 2. Study Guide 73 perfect
solutions
A same-size iron ball and wooden ball are dropped simultaneously from a tower and
reach the ground at the same time. The iron ball has a greater - ANSWER-momentum
A 1000-kg car and a 2000-kg car are hoisted to the same height. Raising the more
massive car 2) requires - ANSWER-twice as much work
The total momentum of a flock of identical birds could be zero only if the birds are -
ANSWER-flying in different directions
The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is
- ANSWER-2000 N
A feather and a coin dropped in a vacuum fall with equal - ANSWER-accelerations
If several balls are thrown straight up with different initial speeds, the quantity that will
have the same value along their paths is their - ANSWER-acceleration
Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters
in the same time. The power expended in raising the 50-kg sack is - ANSWER-the
same
When you jump from an elevated position you usually bend your knees upon reaching
the ground, which makes the time of the contact about 10 times that of a stiff-legged
landing. In this way the average force your body experiences is - ANSWER-about 1/10
as great
Which task requires more work?
-lifting a 50kg sack 2 meters
-lifting a 25kg sack 4 meters - ANSWER-both the same
When Peter tosses an egg against a sagging sheet, the egg doesn't break due to
-reduced impulse
-reduced momentum - ANSWER-neither
A toy elevator is raised from the ground floor to the second floor in 20 seconds. The
power needed using 1000 J of work, is - ANSWER-50 W
, Physics Exam 2. Study Guide 73 perfect
solutions
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in
the same amount of time. Compared with the force that stops the car, the force needed
to stop the truck is - ANSWER-greater
A 2-kg ball is held 4 m above the ground. Relative to the ground its potential energy is -
ANSWER-80 J
When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic
energy of - ANSWER-40 J
A bungee jumper attains a speed of 30 m/s just as the bungee cord begins to stretch. If
the period of stretch is 2 s while coming to a halt, the jumper's average deceleration is
about - ANSWER-1.5g
The change in momentum that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a
wall and bounces back at 2.0 m/s is - ANSWER-6kg m/s
You're driving down the highway and a bug spatters into your windshield. Which
undergoes the greater change in momentum during the time of contact? - ANSWER-
both the same
A 2-kg rifle that is suspended by strings fires a 0.01-kg bullet at 200 m/s. The recoil
velocity of the rifle is about - ANSWER-1 m/s
The work done in pushing a TV set a distance of 2 m with an average force of 20 N is -
ANSWER-40 J`
Two identical gliders slide toward each other on an air track. One moves at 1 m/s and
the other at 2 m/s. They collide, stick, and moves at - ANSWER-1/2 m/s
Two vehicles with equal magnitudes of momentum traveling at right angles to each
other undergo an inelastic collision. The combined wreck moves in a direction -
ANSWER-at 45 degrees to the direction of either car before collision
If a Ping-Pong ball and a golf ball both move in the same direction with the same
amount of kinetic energy, the speed of the Ping-Pong ball must be
-less than the golf ball
-more than the golf ball
- the same - ANSWER-both the same
About 40 J is required to push a crate 4 m across a floor. If the push is in the same
direction as the motion of the crate, the force on the crate is about - ANSWER-10 N
When you and your snowboard are in motion, which of the following can be zero?