Question
Can the work by kinetic friction on an object be positive? Zero?
✓
Answer
Yes. Let us consider a block A which is resting on another block B. Block B is resting on a smooth horizontal surface. Let the coefficient of friction between the blocks be $\mu.$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
If the outer coil of the previous problem is rotated through 90° about a diameter, what would be the magnitude of the magnetic field B at the centre?
A rectangular loop of wire ABCD is kept close to an infinitely long wire carrying a current $\text{I}(\text{t})=\text{I}_0\Big(1-\frac{\text{t}}{\text{T}}\Big)$ for 0 and I(0) = 0 for t > T (Fig). Find the total charge passing through a given point in the loop, in time T. The resistance of the loop is R.
→Answer the following question:
Long distance radio broadcasts use short-wave bands. Why?
Long distance radio broadcasts use short-wave bands. Why?
Obtain the amount of $^{60}_{27}\text{Co}$ necessary to provide a radioactive source of 8.0 mCi strength. The half-life of $^{60}_{27}\text{Co}$ is 5.3 years.
→What will be the total flux through the faces of the cube (Fig.) with side of length a if a charge q is placed at:
- A: a corner of the cube.
- B: mid-point of an edge of the cube.
- C: centre of a face of the cube.
- D: mid-point of B and C.
A uniform wheel of radius R is set into rotation about its axis at an angular speed $\omega.$ This rotating wheel is now placed on a rough horizontal surface with its axis horizontal. Because of friction at the contact, the wheel accelerates forward and its rotation decelerates till the wheel starts pure rolling on the surface. Find the linear speed of the wheel after it starts pure rolling.
→Figure. shows two vessels A and B with rigid walls containing ideal gases. The pressure, temperature and the volume are pA, TA, V in the vessel A and pB, TB, V in the vessel B. The vessels are now connected through a small tube. Show that the pressure p and the temperature T satisfy $\frac{\text{p}}{\text{T}}=\frac{1}{2}\Big(\frac{\text{P}_\text{A}}{\text{T}_\text{A}}+\frac{\text{p}_\text{B}}{\text{T}_\text{B}}\Big)$ when equilibrium is achieved.
→
A pin of length 2.00cm is placed perpendicular to the principal axis of a converging lens. An inverted image of size 1.00cm is formed at a distance of 40.0cm from the pin. Find the focal length of the lens and its distance from the pin.
An electron falls through a distance of $1.5 cm$ in a uniform electric field of magnitude $2.0 \times 10^4 N C ^{-1}$ [Fig. 1.10(a)]. The direction of the field is reversed keeping its magnitude unchanged and a proton falls through the same distance [Fig. 1.10(b)]. Compute the time of fall in each case. Contrast the situation with that of 'free fall under gravity'.
→