ROW 1
A motorcycle is being driven at a speed of 20m/s when brakes are applied to bring it to rest in five seconds. The deceleration produced in this case will be?
4m/s2
The slope of speed - time graph gives
acceleration
A bus increases its speed from 36km/hr to 72km/hr in 10 seconds Its acceleration is
1m/s2
A bus moving along a straight line at 20m/s undergoes an acceleration of 4m/s2. After 2 sec, its speed will be?
28m/s
A: The motion of a car in a circular path with constant speed is always accelerated
R: When a car moves along a circular path, then its direction of speed keeps changing continuously. Due to continuous change in direction, the velocity of car changes. And when velocity changes, the motion is said to be accelerated ( even if speed is constant)
Both A and R ar true and R is correct expalanation of A
A: A body is said to be in motion when its position changes continuously with respect to a moving objects taken as refrence point
R: If a body moves very slowly, then it becomes difficut to observe its movement immediately
A is false but R is true
A: The distance travelled by a moving body cannot be zero but the final displacement of a moving body is zero
R: Distance is a vector quantity whereas displacement is a scalar quantity
A is true and R is false
A: Uniform circular motion is accelerated but uniform linear motion is not accelerated
R: In uniform circular motion, the direction of motion changes continuosly, so uniform circular motion is accelerated. In uniform linear motion the direction of motion is fixed, so uniform linear motion is not accelerated
Both A and R are true, R is a correct explanation of A
A particle moves in a circle with O as centre and AO = OB = 5cm, as radius. It starts from A. Calculate:
a. The distance covered
b. The displacement when it reaches B
π = 3.14
Distance - π * OA = 15.7 cm
Displacement = 2 * OB = 10 cm
A bus accelerates at 2m/s2 for first 10sec after the start and retards at 1m/s2 for next 10 sec. Find the total distance covered by the bus.
Case 1: a = 2m/s2 , u = 0 m/s, t = 10sec
v= u + at = 20m/s
s1 = ut + 1/2 at2 = 100 m
Case 2: a = -1m/s2 , u = 20m/s, t = 10sec
s1 = ut + 1/2 at2 = 150 m
An electron moving with a velocity of 5 x 104 m/s enters into a uniform electric field and acquires a uniform acceleration of 104 m/s2 in the direction of its initial motion. Calculate
a. The time in which the electron would acquire a velocity double of its initial velocity.
b. How much distance the electron would cover in this time?
Final Velocity = v = 2u = 10 x 104 m/s
v= u +at; t = 5sec
s = ut + 1/2 at2
s = 37.5 x104m
A girl rides a bicycle with a speed of 10km/hr for 2hrs and 15 km/hr for next 3 hrs. Find the distance moved by her and average speed.
Distance = v1t1 + v2t2 = 10*2 + 15*3 = 65km
Averag speed = Total distance / Total time
= 65 / 5 = 13km/hr
Draw a V - T graph which represents constant velocity and uniform motion
Straight line
Draw a V - T graph which represents uniform decrease in velocity
Downward slope
Draw a V - T graph which represents non - uniform decrease in velocity
Downward Moving curve
Draw a V - T graph which represents non - uniform increase in velocity
upward curve