Motion in a Straight Line Questions and Answers Part-10

1. The velocity of a bullet is reduced from 200m/s to 100m/s while travelling through a wooden block of thickness 10cm. The retardation, assuming it to be uniform, will be
a) \[10\times 10^{4}m\diagup s^{2}\]
b) \[12\times 10^{4}m\diagup s^{2}\]
c) \[13.5\times 10^{4}m\diagup s^{2}\]
d) \[15\times 10^{4}m\diagup s^{2}\]

Answer: d

2. A body of 5 kg is moving with a velocity of 20 m/s. If a force of 100N is applied on it for 10s in the same direction as its velocity, what will now be the velocity of the body
a) 200 m/s
b) 220 m/s
c) 240 m/s
d) 260 m/s

Answer: b

3. A particle starts from rest, accelerates at \[2 m\diagup s^{2}\]  for 10s and then goes for constant speed for 30s and then decelerates at \[4 m\diagup s^{2}\]  till it stops. What is the distance travelled by it
a) 750 m
b) 800 m
c) 700 m
d) 850 m

Answer: a

4. The engine of a motorcycle can produce a maximum acceleration \[5 m\diagup s^{2}\]. Its brakes can produce a maximum retardation 10 m/s2. What is the minimum time in which it can cover a distance of 1.5 km
a) 30 sec
b) 15 sec
c) 10 sec
d) 5 sec

Answer: a

5. The path of a particle moving under the influence of a force fixed in magnitude and direction is
a) Straight line
b) Circle
c) Parabola
d) Ellipse

Answer: a
Explanation: Straight line

6. A car, moving with a speed of 50 km/hr, can be stopped by brakes after at least 6m. If the same car is moving at a speed of 100 km/hr, the minimum stopping distance is
a) 6m
b) 12m
c) 18m
d) 24m

Answer: d

7. A student is standing at a distance of 50metres from the bus. As soon as the bus begins its motion with an acceleration of \[1 m\diagup s^{2}\], the student starts running towards the bus with a uniform velocity u . Assuming the motion to be along a straight road, the minimum value of u , so that the student is able to catch the bus is
a) \[5 m s^{-1}\]
b) \[8 m s^{-1}\]
c) \[10 m s^{-1}\]
d) \[12 m s^{-1}\]

Answer: c

8. A body A moves with a uniform acceleration a and zero initial velocity. Another body B, starts from the same point moves in the same direction with a constant velocity v . The two bodies meet after a time t . The value of t is
a) \[\frac{2v}{a}\]
b) \[\frac{v}{a}\]
c) \[\frac{v}{2a}\]
d) \[\sqrt{\frac{v}{2a}}\]

Answer: a

9. A particle moves along X-axis in such a way that its coordinate X varies with time t according to the equation \[x=\left(2-5t+6t^{2}\right)m \]    . The initial velocity of the particle is
a) \[-5m \diagup s\]
b) \[6m \diagup s\]
c) \[-3m \diagup s\]
d) \[3m \diagup s\]

Answer: a

10. A car starts from rest and moves with uniform acceleration a on a straight road from time t = 0 to t = T. After that, a constant deceleration brings it to rest. In this process the average speed of the car is
a) \[\frac{aT}{4}\]
b) \[\frac{3aT}{2}\]
c) \[\frac{aT}{2}\]
d) aT

Answer: c