raven2783
- 19
- 0
I'm real rusty on my physics, but here are five simple sample problems we were given, I'd appreciate your help in helping me solve these. Thanks!
(1) A single horizontal 10.0 N force, F acts on a 2.0 kg block which is initially at rest at x=0 m. In response to the force, the block accelerates in the direction of the force and some time later has traveled 20.0 m. Use this information to answer the following three questions:
a. In moving through the 20.0 m displacement, the force F does an amount of work given by?
b. What was the horizontal acceleration of the block in m/s2?
c. What was the speed (in m/s) of the block when it passes the x=20.0 m mark?
(2) Suppose that a computer hard drive has a disk that rotates at a constant speed of 7200 rpm (revolutions per minute).
a. What is the direction of acceleration of a point 2.0 cm from the axis of this rotating disk?
b. What is the magnitude of the acceleration (in m/s2) of a point 2.0cm from the axis of rotation?
(3) Suppose the mass of a 1.0 g match was converted entirely to energy. How many Joules of energy would this create?
(4) A spring with constant 2.0 N/m stores 16.0 J of energy when it is compressed by what distance?
(5) A block of mass M falls a distance D near the surface of the Earth and reaches a speed V. What is the final speed of an identical block which falls a distance 16D?[/B]
F=ma
KE=1/2mv²
a=v²/r
W=FD
W=1/2kx²
s=d/t
yf=yi+vit+1/2at²
3. The Attempt at a Solution
1) A single horizontal 10.0 N force, F acts on a 2.0 kg block which is initially at rest at x=0 m. In response to the force, the block accelerates in the direction of the force and some time later has traveled 20.0 m. Use this information to answer the following three questions:
a) In moving through the 20.0 m displacement, the force F does an amount of work given by?
W=FD
200N·M=10N*20m
b) What was the horizontal acceleration of the block in m/s2?
f/m=a
10N/2kg=5m/s²
c) What was the speed (in m/s) of the block when it passes the x=20.0 m mark?
KE=1/2mv² and I need to think about conservation of energy, and I know s=d/t but I need time... t=d/s but I need speed... hrrm.
2) Suppose that a computer hard drive has a disk that rotates at a constant speed of 7200 rpm (revolutions per minute). What is the direction of acceleration of a point 2.0 cm from the axis of this rotating disk?
This must be toward the axis of rotation?
b) What is the magnitude of the acceleration (in m/s2) of a point 2.0cm from the axis of rotation?
a=v²/r
2cm=.02m
2πr?? involved I really don't know how to approach this one.
3. Suppose the mass of a 1.0 g match was converted entirely to energy. How many Joules of energy would this create?
A lot... I know that..
4. A spring with constant 2.0 N/m stores 16.0 J of energy when it is compressed by what distance?
x=f/k
8m=16/2 ...right?
5. A block of mass M falls a distance D near the surface of the Earth and reaches a speed V. What is the final speed of an identical block which falls a distance 16D?
iv+at for the vf of free-falling objects
xi=xf+vit+1/2at² for the position of free-falling objects.
so 16 times the speed would be 16 times the distance.. I think.
Homework Statement
(1) A single horizontal 10.0 N force, F acts on a 2.0 kg block which is initially at rest at x=0 m. In response to the force, the block accelerates in the direction of the force and some time later has traveled 20.0 m. Use this information to answer the following three questions:
a. In moving through the 20.0 m displacement, the force F does an amount of work given by?
b. What was the horizontal acceleration of the block in m/s2?
c. What was the speed (in m/s) of the block when it passes the x=20.0 m mark?
(2) Suppose that a computer hard drive has a disk that rotates at a constant speed of 7200 rpm (revolutions per minute).
a. What is the direction of acceleration of a point 2.0 cm from the axis of this rotating disk?
b. What is the magnitude of the acceleration (in m/s2) of a point 2.0cm from the axis of rotation?
(3) Suppose the mass of a 1.0 g match was converted entirely to energy. How many Joules of energy would this create?
(4) A spring with constant 2.0 N/m stores 16.0 J of energy when it is compressed by what distance?
(5) A block of mass M falls a distance D near the surface of the Earth and reaches a speed V. What is the final speed of an identical block which falls a distance 16D?[/B]
Homework Equations
F=ma
KE=1/2mv²
a=v²/r
W=FD
W=1/2kx²
s=d/t
yf=yi+vit+1/2at²
3. The Attempt at a Solution
1) A single horizontal 10.0 N force, F acts on a 2.0 kg block which is initially at rest at x=0 m. In response to the force, the block accelerates in the direction of the force and some time later has traveled 20.0 m. Use this information to answer the following three questions:
a) In moving through the 20.0 m displacement, the force F does an amount of work given by?
W=FD
200N·M=10N*20m
b) What was the horizontal acceleration of the block in m/s2?
f/m=a
10N/2kg=5m/s²
c) What was the speed (in m/s) of the block when it passes the x=20.0 m mark?
KE=1/2mv² and I need to think about conservation of energy, and I know s=d/t but I need time... t=d/s but I need speed... hrrm.
2) Suppose that a computer hard drive has a disk that rotates at a constant speed of 7200 rpm (revolutions per minute). What is the direction of acceleration of a point 2.0 cm from the axis of this rotating disk?
This must be toward the axis of rotation?
b) What is the magnitude of the acceleration (in m/s2) of a point 2.0cm from the axis of rotation?
a=v²/r
2cm=.02m
2πr?? involved I really don't know how to approach this one.
3. Suppose the mass of a 1.0 g match was converted entirely to energy. How many Joules of energy would this create?
A lot... I know that..
4. A spring with constant 2.0 N/m stores 16.0 J of energy when it is compressed by what distance?
x=f/k
8m=16/2 ...right?
5. A block of mass M falls a distance D near the surface of the Earth and reaches a speed V. What is the final speed of an identical block which falls a distance 16D?
iv+at for the vf of free-falling objects
xi=xf+vit+1/2at² for the position of free-falling objects.
so 16 times the speed would be 16 times the distance.. I think.
Last edited: