Daily Practice Problems

Class 11 Physics

Motion In A Plane

Class 11 Physics

Motion In A Plane

**Question 1.**

Give definitions for vector and scalar quantities with examples.

**Question 2.**

The position of a particle is given by:

**r **= 5.0t*i* + 2.0t^{2}* ^{j}* + 6.0

where t is in seconds and the coefficients have the proper units for **r **to be in metres.

- Find
**v**(t) and**a**(t) of the particle. - Find the magnitude and direction of
**v**(t) at t = 1.0s.

**Question 3.**

Rain is falling vertically with a speed of 25 m/s. Anita rides a bicycle with a speed of 10 m/s in east to west direction. What is the direction in which she should hold her umbrella?

**Question 4.**

A man stands on the edge of a cliff 500 m above the ground and throws a stone horizontally with an initial speed of 10 m/s. Neglecting air-resistance, find the time taken by the stone to reach the ground, and the speed with which it hits the ground. (Take g = 9.8 m/s^{2}).

**Question 5.**

A cricket ball is thrown at a speed of 30 m/s in a direction 30^{0} above the horizontal. Calculate

- the maximum height,
- the time taken by the ball to return to the same level,
- the distance from the thrower to the point where the ball returns to the same level.

**Question 6.**

What do you understand by a null vector?

**Question 7.**

Define unit vector.

**Question 8.**

The position of a particle is given by

**r = **4.0t*i* + 3.0t^{2}* ^{j}* + 6.0

where t is in seconds and the coefficients have the proper units for **r **to be in metres.

- Find the
**v**and**a**of the particle. - What is the magnitude and direction of velocity of the particle at t = 3.0s?

**Question 9.**

If the velocity of an object changes from v top v’ in time ∆t. What would be the acceleration in this case?

**Question 10.**

An aircraft is flying at a height of 4000 m above the ground. If the angle subtended at a ground observation point by the aircraft positions 10.0s apart is 30^{0} . What is the speed of the aircraft?** **

**Question 11.**

A bullet fired at an angle of 30^{0} with the horizontal hits the ground 6.0 km away. By adjusting its angle of projection, can one hope to hit a target 9.0 km away? Assume that the muzzle speed to be fixed, and neglect air resistance.

**Question 12.**

What do you understand by projectile motion? Give path, maximum height and range of the projectile.

**Question 13.**

A bicyclist is riding with a speed of 30 km/h. As he approaches a circular turn on the road of radius 90 m, he applies brakes and reduces his speed at the constant rate of 0.50 m/s every second. What is the magnitude and direction of the net acceleration of the cyclist on the circular turn?

**Question 14.**

When will you say that an object’s motion is uniform circular motion?

**Question 15.**

A stone tied to the end of a string 100 cm long is whirled in a horizontal circle with a constant speed. If the stone makes 15 revolutions in 30s, what is the magnitude and direction of acceleration of the stone.

**Question 16.**

An ant trapped in a circular groove of radius 10cm moves along the groove steadily and completes 5 revolutions in 50s. What is the angular speed and linear speed of the motion?

**Question 17.**

A cricketer can throw a ball to a maximum horizontal distance of 90m. How much high above the ground can the cricketer throw the same ball?

**Question 18.**

A particle starts from origin at t=0 with a velocity 6.0*i* m/s and moves in x-y plane under action of a force, which produces a constant acceleration of (4.0*i* + 3.0* ^{j}* )m/s

- What is the y- coordinate of the particle at the instant its x-coordinate is 96m?
- What is the speed of the particle at this time?

**Question 19.**

A motorboat is racing towards north at 30km/h and the water current in that region is 15km/h in the direction of 30^{0} east of south. Find the resultant velocity of the boat.

**Question 20.**

Is path length traversed by an object same as the magnitude of displacement?

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