If M = Mass, L = Length, T = Time and I = Electric current, then the dimensional formula for electrical resistance R is given by

• [R] = [M¹L²T^-3I^-2]

• [R] = [M¹L²T^-3I²]

• [R] = [M¹L²T³I^-2]

• [R] = [M¹L²T³I²]

12.

A body is moving at a speed near 0.3 ms^-1. To measure its speed with an accuracy about 1%, using a sampling distance 3 mm, the measuring clock should have a least count of the order of

• 0.1 s

• 0.01 s

• 0.001 s

• 0.0001 s

A train moves from one station to another in 2 hours time. Its speed-time graph during this motion is shown below. The maximum acceleration during the journey is

• 140 kmh^-2

• 160 kmh^-2

• 100 kmh^-2

• 120 kmh^-2

A body dropped from a height h with an initial speed zero reaches the ground with a velocity of 3 km/h. Another body of the same mass was dropped from the same height h with an initial speed 4 km/h will reach the ground with a velocity of

• 3 km/h

• 4 km/h

• 5 km/h

• 12 km/h

If the acceleration due to gravity is 10 ms^-2 and the units of length and time are changed to kilometre and hour respectively, the numerical value of the acceleration due to gravity is

• 360000

• 72000

• 36000

• 129600

A boat man can row with a speed of 10 km/h in still water. If the river flows at 5 km/h, the direction in which the boat man should row to reach a point on the other bank directly opposite to the point from where he started is (width of the river is 2 km)

• in a direction inclined at 120° to the direction of river flow

• in a direction inclined at 90° to the direction of river flow

• 60° in the north-west direction

• should row directly along the river flow

The maximum and minimum magnitudes of the resultant of two given vectors are 17 units and 7 units respectively. If these two vectors are at right angles to each other, the magnitude of their resultant is

• 14

• 16

• 18

• 13

A cricketer can throw a ball to a maximum horizontal distance of 100 m. The speed with which he throws the ball is (to the nearest integer)

• 30 ms^-1

• 42 ms^-1

• 32 ms^-1

• 35 ms^-1

A box whose mass is 5 kg lies on a spring balance inside a lift. The lift starts to ascend with an acceleration of 2 ms^-2. The reading of the machine or balance is (g = 10 ms^-2)

• 50 kg

• zero

• 49 kg

• 60 kg

A ball of mass 0.5 kg moving with a velocity of 2 ms^-1 strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and wall is 10^-3 s, the average force exerted by the wall on the ball is

• 1125 N

• 1000 N

• 500 N

• 2000 N