Advertisements
Advertisements
प्रश्न
A car of mass m starts from rest and acquires a velocity along east `v = vhati (v > 0)` in two seconds. Assuming the car moves with uniform acceleration, the force exerted on the car is ______.
पर्याय
`(mv)/2` eastward and is exerted by the car engine.
`(mv)/2` eastward and is due to the friction on the tyres exerted by the road.
more than `(mv)/2` eastward exerted due to the engine and overcomes the friction of the road.
`(mv)/2` exerted by the engine.
Advertisements
उत्तर
A car of mass m starts from rest and acquires a velocity along east `v = vhati (v > 0)` in two seconds. Assuming the car moves with uniform acceleration, the force exerted on the car is `underline((mv)/2)` eastward and is due to the friction on the tyres exerted by the road.
Explanation:
Given, the mass of the car = m
As the car starts from rest, u = 0
Velocity acquired along east = `vhati`
Duration = t = 2s.
We know that v = u + at
⇒ `vhati = o + a xx 2`
⇒ `s = v/2 hati`
Force, F = ma = `(mv)/2 hati`
Hence, the force acting on the car is `(mv)/2` towards the east. As the external force on the system is only friction hence, the force `(mv)/2` is by friction. Hence, force by the engine is internal force.
APPEARS IN
संबंधित प्रश्न
A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because ______.
Give the magnitude and direction of the net force acting on a drop of rain falling down with a constant speed.
Define one newton force.
Find the acceleration produced by a force of 5 N acting on a mass of 10 kg.
The acceleration of a particle is zero, as measured from an inertial frame of reference. Can we conclude that no force acts on the particle?
A block of mass 2 kg placed on a long frictionless horizontal table is pulled horizontally by a constant force F. It is found to move 10 m in the first seconds. Find the magnitude of F.
A block of 2 kg is suspended from a ceiling by a massless spring of spring constant k = 100 N/m. What is the elongation of the spring? If another 1 kg is added to the block, what would be the further elongation?
When a train starts, the head of a standing passenger seems to be pushed backward. Analyse the situation from the ground frame. Does it really go backward? Coming back to the train frame, how do you explain the backward movement of the head on the basis of Newton's laws?
State Newton's first law of motion.
Derive the relation between newton and dyne.
Name the different kinds of inertia an object can possess. Give an example of each.
The amount of inertia of a body depends on its _________.
Differentiate between gravitational mass and inertial mass.
Match the following
| Column I | Column II |
| Newton’s I law | propulsion of a rocket |
| Newton’s II law | Stable equilibrium of a body |
| Newton’s III law | Law of force |
| Law of conservation of linear momentum | Flying nature of bird |
Block A of weight 100 N rests on a frictionless inclined plane of slope angle 30° (figure). A flexible cord attached to A passes over a frictonless pulley and is connected to block B of weight W. Find the weight W for which the system is in equilibrium.
A balloon has mass of 10 g in air. The air escapes from the balloon at a uniform rate with velocity 4.5 cm/s. If the balloon shrinks in 5 s completely. Then, the average force acting on that balloon will be (in dyne).
What is the significance of Newton’s first law?
