Category: General Physics

  • How much Energy is Stored?

    How much energy can be stored in a spring with k = 490 N/m if the maximum possible stretch is 20 cm? Known variables: k=490 x= 20cm or .2m Kinetic Energy Equation K.E= 1/2kx2 Once you know your variables and your equation, just plug it in. K.E= .5 x (490) x (.2)2 K.E= 9.8 J

  • How much Thermal Energy is Created?

    Marissa drags a 22 kg duffel bag 16 m across the gym floor. If the coefficient of kinetic friction between the floor and bag is 0.15 , how much thermal energy does Marissa create? Known variables: mass (m)= 22 kg drag (s)=16 m coefficient of kinetic friction=(μ) .15 gravity (g)= 9.8 thermal energy equation: μ*m*g*s μ      …

  • Minimum Speed

    With what minimum speed must you toss a 100 ball straight up to hit the 14 -high roof of the gymnasium if you release the ball 1.4 above the ground? Solve this problem using energy. Work is the same as change in energy You can figure out how much gravitational potential energy the ball has…

  • What is the Landing Speed?

    As a 15000 kg jet plane lands on an aircraft carrier, its tail hook snags a cable to slow it down. The cable is attached to a spring with spring constant 60000 N/m. If the spring stretches 30 m to stop the plane, what was the plane’s landing speed? Variables known: m= 15000 kg k= 60000 N/m…

  • How much Work?

    1) How much work does an elevator motor do to lift a 1000 kg elevator a height of 100 m? Known variables: mass (m): 1000 kg height (h): 100m Work = Force x Distance We need to find a force. Since there is gravity, all we have to do is multiply it by the mass…

  • Final Velocities : Elastic

    Ball 1, with a mass of 100 g and traveling at 15 m/s, collides head on with ball 2, which has a mass of 350 g and is initially at rest. What are the final velocities of each ball if the collision is perfectly elastic? Known variables: Mass(m1) of the first ball = 100 g or .100 kg Initial velocity (v1) of…

  • Same Momentum

    At what speed do a bicycle and its rider, with a combined mass of 100 kg, have the same momentum as a1300 kg car traveling at 6.0 m/s? Known variables: (mass of bicycle) m1= 100 kg (mass of car) m2= 1300kg (velocity of car) v2 = 6.0 m/s   Momentum is mass  x  velocity.   =>  m1  x  v1  =  m2…

  • What Impulse was Applied?

    A 57 g tennis ball is served at 45 m/s. If the ball started from rest, what impulse was applied to the ball by the racket? Known Variables: mass(m) : 57g or .057 kg velocity(v) : 45 m/s Impulse is force and time I = F x t We know that   F= ma & a=v/t this would be derived F= m (v/t) Since we…

  • What is the Mass?

    An ice hockey puck slides along the ice at 12 m/s. A hockey stick delivers an impulse of 4.0 kg * m/s causing the puck to move off in the opposite direction with the same speed. What is the mass of the puck? Known variables: initial velocity (v1) : 12 m/s final velocity (v2) : -12 m/s   (opposite direction)…

  • What is the Magnitude of the Impulse Delivered?

    In a Little League baseball game, the 145 g ball enters the strike zone with a speed of 15.0 m/s. The batter hits the ball, and it leaves his bat with a speed of 20.0 m/s in exactly the opposite direction. 1) What is the magnitude of the impulse delivered by the bat to the ball? Known Variables: (ball) mass…