1) For a velocity graph of an object that is at the origin (x=0) at t=0s. At t=4

Question

1) For a velocity graph of an object that is at the origin (x=0) at t=0s. At t=4s, what is the objects position?

2) How long does a pen fall from a 1.2 m high table (ignore air drag). p.s. I solved for t with the distance formula but when I go to square it at the end I get 22 seconds for my answer, however the answer is supposed to be 49 seconds.

3) An object, when pushed with a net force F, has an acceleration of 2 m/s^2. Now twice the force is applied to an object that has four times the mass. Its acceleration will then be?

4) A ball at the end of a string (length of the string is 45 cm) is being swung at a constant speed in a horizontal circle. The ball makes 2.5 rotations per second. What is the speed of the ball?

5) We measured the energy consumption of a lamp for one hour to be 270kJ. What is it's power?

Explanation / Answer

1) Please upload a graph for exact values, the general procedure is as follows,

since,

v =ds/dt

so,

ds = v.dt

thus, the area of the V-T curve will give the displacement at different times.......

2)

h=vit+1/2 gt^2

1.2= 0 +1/2* 9.8*t^2

t^2= 0.244

==> t=0.49 sec (not 49 sec as u said)

3)

As, force= mass*acceleration,

f=ma

for given condition,

f= 2m. ...................(i)

Now, for f= 2f, m= 4m, the above equation will be,

2f= 4m*a ==> 2 (2m)= 4m*a (here, plug in equation (i))

a=1 m/sec^2,

4)

length of string=0.45 m

rotation speed   n = 2.5 rev/s

angular velocity w = 2(pi) n = 6.28 (2.5 ) = 15.7 rad/s

now

v=rw ===> v=0.45*15.7

v=7.065 m/sec

5)

Power= energy /time

P= 270KJ/3600 sec

P= 0.075 KW

or

P= 75 Watt.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.