this is a physics question see if you can help...appreciate it.
1. An object has a kinetic energy of
231
J and a momentum of magnitude
26.8
kg
·
m/s. Find
the speed and the mass of the object.
speed
-------- m/s
mass
----------- kg
2.
At one instant, a
15.0
-kg sled is moving over a horizontal surface of snow at
4.60
m/s.
After
6.05
s has elapsed, the sled stops. Use a momentum approach to ±nd the magnitude
of the average friction force acting on the sled while it was moving.
--------------
N
3.
A
45.8
-kg girl is standing on a
153
-kg plank. Both originally at rest on a frozen lake that
constitutes a frictionless, ²at surface. The girl begins to walk along the plank at a constant
velocity of
1.58
î
m/s relative to the plank.
(a) What is the velocity of the plank relative to the ice surface?
--------------
î
m/s
(b) What is the girl's velocity relative to the ice surface?
-------------
î
m/s
4.
A man claims that he can hold onto a
16.0
-kg child in a head-on collision as long as he has
his seat belt on. Consider this man in a collision in which he is in one of two identical cars
each traveling toward the other at
62.0
mi/h relative to the ground. The car in which he rides
is brought to rest in
0.08
s.
(a) Find the magnitude of the average force needed to hold onto the child.
--------------
N
(b) Based on your result to part (a), is the man's claim valid?
-----------
This man's claim is nonsense.
------------
This man's claim is legitimate.
5.
An estimated force–time curve for a baseball struck by a bat is shown in the ±gure below.
Let
F
max
=
16,000
N,
t
a
=
1.5
ms, and
t
b
=
2
ms. From this curve, determine the following.
(a) the magnitude of the impulse delivered to the ball
--------------
N
·
s
(b) the average force exerted on the ball
-------------------
kN
6.
After a
0.320
-kg rubber ball is dropped from a height of
18.5
m, it bounces oF a concrete
±oor and rebounds to a height of
15.0
m.
(a) Determine the magnitude and direction of the impulse delivered to the ball by the ±oor.
magnitude -----------
kg
·
m/s
direction
---Select--- right left up down
(b) Estimate the time the ball is in contact with the ±oor to be
0.04
seconds. Calculate the
average force the ±oor exerts on the ball.
magnitude ----------
N
direction
---Select--- right left up down
7.
.
In a slow-pitch softball game, a 0.200-kg softball crosses the plate at
19.0
m/s at an angle
of
40.0
° below the horizontal. The batter hits the ball toward center ²eld, giving it a velocity
of
46.0
m/s at 30.0° above the horizontal. (Take positive
î
to be the horizontal direction from
the plate toward center ²eld and take positive
ĵ
to be the upward vertical direction.)
(a) Determine the impulse delivered to the ball.
= -----------------
N.s
(b) If the force on the ball increases linearly for 4.00 ms, holds constant for 20.0 ms, and
then decreases linearly to zero in another 4.00 ms, what is the maximum force on the ball?
= ---------------
N
8.
