Need Help Reviewing Your Physics Assignment Answers?

[butz3]

i have this pratice assignment that i would like some one to double check to make sure i did it right. if I got the question wrong would you please explain what i did wrong thaks so much so here it goes.
Multiple Choise
1) th unit that is equivalent to a joule is found my manipulating units of
a) force x distance/ time
b) force/ acceleration
c) mass x speed squared - this is what i picked
d) work/ mass
2)an experiment was done by measuring the work done moving an object with mass m up a ladder. work was calculated by measuring the force needed to lift the object and multiplying it by the distance moved. an algebraic value for the slope of this is
a) mg
b)g - this is what i picked
c)m
d)1/g
3) two cars collide and stick together on a frictionless, horizontal surface. which of the following statements is likely true?
a)momentum will not be conserved and kinetic energy will not be conserved
b)momentum will be conserved and kinetic energy will not be conserved - i picked this one
c)both momentum and kinetic energy will be conserved
d)momentum will not be conserved and kinetic energy will be conserved
4)during and experiment with simple harmonic motion, a group of students used the period of a pendulum to calculate g, the acceleration due to gravity. they measured the period and the length of the pendulum. the value of g is found by using which of these equations?
a) g=4pie^2l/t^2- i picked this one
b)g=4piel/t^2
c)g=2piesquare root l/t
d)g=t^2/4pie^2l
5)if the distance between two charges was doubled, the resulting force of electrostatic attration would be
a)the same
b)half as great
c)twice as great
d)one quarter as great - i picked this one
6)a positive charge moves form left to right across a magnetic field and experiences a magnetic force which is directed upwards along the page. the direction of the external magnetic field is?
a)left to right
b)right to left
c)directed into the plane of the page
d)directed out of the plane of the page - i picke this one.
numerical responce
1)a 6.00 kg steel ball falls of a ledge that is 4.50 m high. its speed upon impcat is N m/s. the value of n is? my answer is 9.40m/s
2)a hair dryer draws 1.5A form a 120V source. if the hair dryer is used for 10 min the energy consumed is b x 10^w J. the value for b is? my answer is 1.1X10^5 J
3)an alpha particle which possesses 1.36x10^-13 J of kinetic energy enters a magnetic field of 4.60x10^-3T. the deflecting force on the alpha paricle is b x10^-w N. the value for b is? my answer is 4.7x 10^-15N.

thanks for your help

 

[dextercioby]

Review questions 2 and 6.
At tha last i trust u on the numbers:
F=qvB.They're not relativistic,so i should be okay...


Daniel.

 

[wais]

Sure, I would be happy to double check your practice assignment. I'll go through each question and provide feedback on your answers.

1) The correct answer is actually (b) force/acceleration. The unit for work is force x distance, and the unit for force is mass x acceleration. So when you divide force by acceleration, you get the unit for work, which is joules.

2) You are correct, the algebraic value for the slope of the work vs. distance graph would be (b) g, since work is equal to force x distance and force is equal to mass x acceleration. So the slope would be equal to mass x acceleration, which is just mg.

3) The correct answer is actually (c) both momentum and kinetic energy will be conserved. This is because in a collision on a frictionless surface, there is no external force acting on the system, so both momentum and kinetic energy will be conserved.

4) The correct equation to find g using the period of a pendulum is (c) g=4pi^2L/T^2. This is derived from the equation for the period of a pendulum, T=2pi(square root of L/g).

5) You are correct, the resulting force of electrostatic attraction would be (d) one quarter as great. This is because the force between two charges is inversely proportional to the square of the distance between them. So if the distance is doubled, the force would decrease by a factor of 4.

6) You are correct, the direction of the external magnetic field would be (d) directed out of the plane of the page. This is because the magnetic force on a positively charged particle moving through a magnetic field is perpendicular to both the velocity of the particle and the magnetic field, and is given by the right-hand rule.

Numerical response:
1) Your answer of 9.40 m/s is correct. Good job!
2) Your answer of 1.1 x 10^5 J is also correct. Well done!
3) Your answer for b is correct, but the value for w should be -12, not -15. The final answer would be 4.7 x 10^-12 N. Great work overall!

Overall, you did a great job on this practice assignment. Keep up the good work! Remember to always double check your units and equations to ensure you are using the correct ones. If you