The percentage errors in the measurement of length and time period of a simple pendulum are 1% and 2% respectively. Then the maximum error in the measurement of acceleration due to gravity is
8 %
3 %
5 %
6 %
A body is falling freely under gravity. The distances covered by the body in first, second and third minute of its motion are in the ratio
1 : 4 : 9
1 : 2 : 3
1 : 3 : 5
1 : 5 : 6
A bullet fired into a fixed wooden block loses half of its velocity after penetrating 40 cm. It comes to rest after penetrating a further distance of
A ball A is thrown up vertically with a speed u and at the same instant another ball B is released from a height h. At time t, the speed of A relative to B is
u
2u
u − gt
A bullet is to be fired with a speed of 2000 ms-1 to hit a target 200 m away on a level ground. If g = 10 ms-2, the gun should be aimed
directly at the target
5 cm below the target
5 cm above the target
2 cm above the target
C.
5 cm above the target
Horizontal distance of target is 200 m.
Speed of bullet = 2000 ms-1
Time taken by bullet to cover the horizontal distance
During s, the bullet will fall down vertically due to gravitational acceleration.
Therefore, height above the target, so that the bullet hits the target is
The resultant of two vectors and is . If the magnitude of is doubled, the new resultant becomes perpendicular to . Then the magnitude of is
P + Q
Q
P
A motor car is moving with a speed of 20 ms-1 on a circular track of radius 100 m. If its speed is increasing at the, rate of 3 ms-1, its resultant acceleration is
3 ms-2
5 ms-2
2.5 ms-2
3.5 ms-2
A stationary body of mass 3 kg explodes into three equal pieces. Two of the pieces fly off in two mutually perpendicular directions, one with a velocity of ms-1 and the other with a velocity of ms-1. If the explosion occurs in 10-4 s, the average force acting on the third piece in newton is
A mass of 1 kg is just able to slide down the slope of an inclined rough surface when the angle of inclination is 60°. The minimum force necessary to pull the mass up the inclined plane (g = 10 ms-2) is
14.14 N
17.32 N
10 N
16.66 N