A bullet is fired from a gun. The force on the bullet is given by F=600-2×105t. where F is in newton and t in seconds. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to the bullet?
9 N
zero
1.8 N
0.9 N
A passenger in the bus finds that his suit case suddenly starts sliding backwards. This means that the bus is
turning left
turning right
accelerating
retarding
A body takes time t to reach the bottom of an inclined plane of angle θ with the horizontal. If the plane is made rough, time taken now is 2t. The coefficient of friction of the rough surface is
Starting from rest, a body slides down as 450 inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is
0.80
0.75
0.25
0.33
A block of 10 kg is pulled at a constant speed on a rough horizontal surface by a force of 20 N.Find the co- effecient of kinetic friction ?Given that g = 10 m/s2 .
0.2
0.5
0.85
0.7
A body of mass 10 kg lies on a rough horizontal surface. When a horizontal force of F newtons acts on it, it gets an acceleration of 5 m/s2 and when the horizontal force is doubled, it gets an acceleration of 18 m/s2. The coefficient of friction between the body and the horizontal surface (assume g=10m/s2) is
0.6
0.4
0.8
If the force on a rocket moving with a velocity of 300 m/s is 345 N, then the rate of combustion of the fuel is
0.55 kg/s
0.75 kg/s
1.15 kg/s
2.25 kg/s
A block of mass 50 kg just slides over a horizontal distance of 1 m. If coefficient of friction between their surfaces is 0.2, the work done against friction is
98 J
56 J
72 J
34 J
A 600 kg rocket is set for a vertical firing.If the exhaust speed is 1000 m/s,the mass of the gas ejected per second to supply the thrust needed to overcome the weight of rocket is
117.6 kgs-1
58.6 kgs-1
6 kgs-1
76.4 kgs-1
A shell is fired from a canon, it explodes in mid air, its total
momentum increases
momentum decreases
KE increases
KE decreases
