Physics Motion in Straight Line

A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity $4{\mathrm{m}\mathrm{s}}^{-1}$ . The ball strikes the water surface after $4\mathrm{s}$ . The height of bridge above water surface is (Take $\mathrm{g}=$ $10{\mathrm{m}\mathrm{s}}^{-2}$  ):

A vehicle travels half the distance with speed V and the remaining distance with speed 2v. Its average speed is:

The ratio of the distances travelled by a freely falling body in the $1^{\text{st}},2^{\text{nd}},3^{\text{rd}}$ and $4^{\text{th}}$  second:

The displacement-time graphs of two moving particles make angle of ${30}^{?}$ and ${45}^{?}$ with the $x$ -axis as shown in the figure. The ratio of their respective velocity is :

The position, velocity and acceleration of a particle moving with a constant acceleration can be represented by:

A car accelerates from rest at a constant rate α for some time after which it decelerates at a constant rate β to come to rest. If the total time elapsed is t seconds, the total distance traveled is :

The speed verses time graph for a particle is shown in the figure. The distance travelled (in m ) by the particle during the time interval t = 0 to t = 5 s will be .

Train A and train B are running on parallel tracks in opposite directions with speed of 36 km/hour and 72 km/hour, respectively. A person is walking in train A in the direction opposite to its motion with a speed of 1.8 km/hour. Speed (in ms⁻¹) of this person as observed from train B will be close to: (take the distance between the tracks as negligible)