A 750 g air glider is motionless on an air track until acted upon by the force t

Question

A 750 g air glider is motionless on an air track until acted upon by the force that is plotted below. 1. Calculate the impulse acting on the cart. 2. Calculate the new velocity of the cart after the impulse. 3. Suppose the 750 g glider, now moving at the speed you just calculated, strikes a motionless 500 g glider and the two stick together. How fast is the combination moving immediately after the collision? 4. If the collision lasted 10 ms, what average force acted on the two carts? ( Time is plotted on the x axis. 0-6 seconds is the base of the triangle @ 4 seconds the tip of the triangle is @ 400 N on the y axis.)

Explanation / Answer

Construct free-body diagrams for the following physical situations. a. A ball is dropped from rest from the top of a building. Assume negligible air resistance. In the absence of Fair, the only force acting upon the ball is gravity. It is a projectile. b. After being thrown, a football is moving upwards and rightwards towards the peak of its trajectory. Assume negligible air resistance. In the absence of Fair, the only force acting upon the ball is gravity. It is a projectile. Note that an upwards moving object does not need an upwards force. Only an upwards accelerating object requires an upwards force. c. After reaching a terminal velocity, a falling skydiver then opens up the parachute. When the terminal velocity was reached, Fair = Fgrav. Then the parachute was opened, making Fair even greater than before. This is represented by the larger arrow. d. An air track glider is gliding to the right at constant velocity. There is no rightwards force. A rightwards force would only be required if there is a rightwards acceleration. If the glider is gliding; there is no mention of it being pushed or pulled (Fapp) and if there is a constant velocity, there must be balanced forces. e. A car is skidding to a stop while travling to the right. There is no rightwards force. A rightwards force would only be required if there is a rightwards acceleration. If the car is skidding (wheels are locked), friction acts in a direction opposite its motion to slow it down. f. A downward moving elevator (held by a cable) slows down. The cable supplies the tension force. Since the elevator is moving downwards and slowing down, there must be more upwards force than the downwards gravity force. g. A 25.0-N force is applied at a 30-degree angle to a crate in order to accelerate it rightward across a rough, horizontal surface. The applied force is upwards and rightwards. Its upward component contributes to the upwards Fnorm to balance the force of gravity. (Note the relative size of Fnorm.) h. A picture hangs summetrically by two wires oriented at angles to the vertical. The force exerted by a wire is a tension force. With two wires, there would be two upwards-pulling tension forces. The down force is gravity. i. A large crate slowly accelerated down a steep and rough inclined plane. There are only three forces present. The Fpar and Fperp are merely components of gravity; they are not separate forces. The normal force is perpendicular to the surface (drawn in blue).

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