Advertisements
Advertisements
Question
A long stick rests on the surface. A person standing 10 m away from the stick. With what minimum speed an object of mass 0.5 kg should he has thrown so that it hits the stick. (Assume the coefficient of kinetic friction is 0.7).
Advertisements
Solution
Given,
Distance (s) = 10 m
Mass of the object (m) = 0.5 kg
Coefficient of kinetic friction (µ) = 0.7
Work done in moving a body in horizontal surface ω
= µR × s = µmg × s
This work done is equal to initial kinetic energy of the object
`1/2mv^2` = µ mg s
∣`v^2`∣ = 2 µgs = 2 × 0.7 × 9.8 × 10
v2 = 14 × 9.8 = 137. 2
v = 11. 71 ms-1
APPEARS IN
RELATED QUESTIONS
State the empirical laws of static and kinetic friction.
Briefly explain ‘rolling friction.'
Briefly explain the origin of friction. Show that in an inclined plane, the angle of friction is equal to the angle of repose.
A uniform metal chain is placed on a rough table such that one end of the chain hangs down over the edge of the table. When two-thirds of its chain length hangs over the edge the chain start sliding. Then the coefficient of static friction is:
A block of mass 20 kg is sliding on a surface is inclined at an angle of 45° with the horizontal. What will be the acceleration of the block if the coefficient of kinetic friction between the block and the surface is 0.7?
A block of mass m slides along a floor while a force of magnitude F is applied to it at an angle θ as shown in figure. The coefficient of kinetic friction is µK. Then, the block's acceleration 'a' is given by ______.
(g is acceleration due to gravity)
A 40 kg wooden crate is being pushed across a wooden floor with a force of 160 N. If µk = 0.3, the acceleration of the crate is ______ m/s2. (g = 10 m/s2}
A block of mass m = 1 kg moving on horizontal surface with speed u = 2 m/s enters a rough horizontal patch ranging from x = 0.10 m to x = 2.00 m. If the retarding force fr on the block in this range is inversely proportional to x over this range i.e.
fr = `"-k"/x` 0.10 < x < 2.00
= 0 for x < 0.10 and x > 2.00
If k = 0.5 J then the speed of this block as it crosses the patch is (use ℓn 20 = 3)
The coefficient of static friction between a car's tires and a level road is 0.80. If the car is to be stopped in a maximum time of 3.0 s, its speed cannot exceed.
A body starts from rest on a long inclined plane of slope 45°. The coefficient of friction between the body and the plane varies as µ = 0.3 x, where x is distance travelled down the plane. The body will have maximum speed (for g = 10 m/s2) when x = ______.
