1. STATEMENT-1: A particle having negative acceleration will slow down.
STATEMENT-2 : Direction of the acceleration is not dependent upon direction of the velocity.
1. (A) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is correct explanation for STATEMENT-1
(B) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is not correct explanation for STATEMENT-1
(C) STATEMENT-1 is true, STATEMENT-2 is false (D) STATEMENT-1 is false, STATEMENT-2 is true (E) Both STATEMENTS are false
2. STATEMENT-1 : Magnitude of average velocity is equal to average speed.
STATEMENT-2 : Magnitude of instantaneous velocity is equal to instantaneous speed.
(A) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is correct explanation for STATEMENT-1
(B) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is not correct explanation for STATEMENT-1
(C) STATEMENT-1 is true, STATEMENT-2 is false (D) STATEMENT-1 is false, STATEMENT-2 is true (E) Both STATEMENTS are false
3. STATEMENT-1 : When velocity of a particle is zero then acceleration of particle must be zero at that
instant.
STATEMENT-2 : Acceleration is equal to dx dv v
a , where v is the velocity at that instant..
(A) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is correct explanation for STATEMENT-1
(B) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is not correct explanation for STATEMENT-1
(C) STATEMENT-1 is true, STATEMENT-2 is false (D) STATEMENT-1 is false, STATEMENT-2 is true (E) Both STATEMENTS are false
4. STATEMENT-1 : A particle moves in a straight line with constant accleration. The average velocity of
this particle cannot be zero in any time interval
STATEMENT-2 : For a particle moving in straight line with constant acceleration, the average velocity
in a time interval is 2
v u
, where u and v are initial and final velocity of the particle in the given time interval.
(A) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is correct explanation for STATEMENT-1
(B) STATEMENT-1 is true, STATEMENT-2 is true and STATEMENT-2 is not correct explanation for STATEMENT-1
(C) STATEMENT-1 is true, STATEMENT-2 is false (D) STATEMENT-1 is false, STATEMENT-2 is true (E) Both STATEMENTS are false
PART - I : SUBJECTIVE QUESTIONS
1. Figure shows four paths along which objects move from a starting point to a final point (particle is moving along the same straight line), all in the same time. The paths pass over a grid of equally spaced straight lines. Rank the paths according to
(a) the magnitude of average velocity of the objects (b) the average speed of the objects, greatest first.
2. A particle moving in straight line, traversed half the distance with a velocity v0. The remaining part of the distance was covered with velocity v1 for half the time and with velocity v2 for the other half of the time. Find the mean velocity of the particle averaged over the whole time of motion.
3. The displacement of a particle moving on a straight line is given by x = 16t – 2t2. Find out
(a) Displacement upto 2 and 6 s. (b) Distance travelled upto 2 and 6 s.
4. A man walking with a speed 'v' constant in magnitude and direction passes under a lantern hanging at a height H above the ground (consider lantern as a point source). Find the velocity with which the edge of the shadow of the man's head moves over the ground, if his height is 'h'.
5. A police jeep is chasing a culprit going on a moter bike. The motor bike crosses a turn at a speed of 72 km/ h. The jeep follows it at a speed of 108 km/h, crossing the turn 10 seconds later than bike (keeping constant speed). After crossing the turn, jeep acclerates with constant accleration 2 m/s2. Assuming bike travels at constant speed, how far from the turn will the jeep catch the bike?
6. A healthy youngman standing at a distance of 6 m from a 11.5 m high building sees a kid slipping from the top floor. With what uniform acceleration (starting from rest) should he run to catch the kid at the arms height (1.5 m)? Take g = 10 m/s2.
7. A lift is descending with uniform acceleration. To measure the acceleration , a person in the lift drops a coin at the moment when lift was descending with speed 6 ft/s. The coin is 5 ft above the floor of the lift at time it is dropped. The person observes that the coin strikes the floor in 1 second. Calculate from these data, the acceleration of the lift. [Take g = 32 ft/s2]
8. A body starts with an initial velocity of 10 m/s and moves along a straight line with a constant acceleration. When the velocity of the particle becomes 50 m/s the acceleration is reversed in direction without changing magnitude. Find the velocity of the particle when it reaches the starting point.
9. The accompanying figure shows the velocity v of a particle moving on a coordinate line.
-4 2
(m/s)
(a) When does the particle move forward? move backward? Speed up? slow down? (b) When is the particle's acceleration positive? Negative ? zero?
(c) When does the particle move at its greatest speed ? (d) When does the particle stand still for more than an instant?
10. A point moves rectilinearly in one direction. Fig. shows
the displacement s traversed by the point as a function of the time t. Using the plot find:
(a) the average velocity of the point during the time of motion;
(b) the maximum velocity;
(c) the time t0 at which the instantaneous velocity is equal to the mean velocity averaged over the first t0 seconds.
11. A lift starts from the top of a m ine shaft and descends with a constant speed of 10m/s. 4 s later a boy throws a stone vertically upwards from the top of the shaft with a speed of 30m/s. Find when and where stone hits the lift.[ Take: g = 10m/s² ]